Accredited Museum

Please Note: Not all of the objects on this website are on display at the museum.

Office, Scientific, Vehicle Products, Valves, Microphones, Galvonometers, Test and Measurement

GENTS MASTER CLOCK, 1950's

Gledhill and Brook put their name on it, and Gents of Leicester supplied it, Parsons and Ball Manufacturing made it. Using the 'Hipp and Toggle' or Gents renamed 'pulsynetic' principal which swings and impulses the pendulum with a gravity bar every 30 seconds. The gravity bar is then raised and reset using a magnetic solenoid. It is different from the GPO clock Item A0073 which also uses a simpler 'Hipp and Toggle' principal
Removed from The Whippendell Electric Works in Watford.


SEE http://west-penwith.org.uk/misc/gent.htm

A0949

GLEDHILL BROOK/GENTS SLAVE CLOCK, 1940's

Gents of Leicester Slave clock supplied by Gledhill Brook for Master clock unit Item A0949, and donated by the Wemco factory in Whippendell Road Watford.

A1327

WORKS CLOCKING MACHINE & CARD RACK, 1950's

This is an example of a time clock used for employees to log starting and finishing times. Inside one of the card slots was a punch card dated 10 Nov 1943, a lady whose name is creased out, was five to six minutes late every morning, 15 minutes would have been docked from her pay every day that she was late.
Removed from The Whippendell Electric Works in Watford. Driven by a long case clock Item A0949,

A0783

NATIONAL TIME RECORDERS FACTORY BELL TIMER AND CLOCK, 1950's

It would appear that although Blick became the main user of National Time Recorders, NTR continued to supply recorders under their own name , an instruction book (not in the museum's possession) which gives Cray Avenue, St Mary Cray, Kent, as the Factory and head office address and shows that the company at that time had branch offices and local service departments in London, Birmingham, Bristol, Dublin, Glasgow, Leeds, Manchester, Newcastle and Sheffield. The booklet is unfortunately undated but the telephone number for the London office was 01-928 6641.

A1291

FACTORY BELL TIMER UNIT, 1950's

Removed from The Whippendell Electric Works in Watford. Driven by a long case clock Item A0949, and used to ring bells for tea breaks, clocking on and off times etc. In use during the second World War, and was installed long before that.

A0824

NIGHT-WATCHMAN TOUR CLOCK, 1950's

Night Watchmen had to carry this clock to prove they had carried out their tour correctly and at the correct times.

A1143

NIGHT WATCHMAN'S ELECTRIC LAMP, 1930's

Fitted with two Edison Type BS 1.5 volt batteries.

A0213

DIRECT CURRENT ELECTRICITY METER, 1930's

The National Grid was introduced in 1926. Power Stations such as Battersea, built in 1933, were to supply a grid of constant power to the entire nation. However building the plants and installing the power lines took nearly ten years.

Some homes up to the Second World War were still using gas or limited electricity from local private companies, some supplying Direct Current of 110 volts. Early wireless's would be battery only, and DC was more convenient.

This equipment was driven by an escapement which was wound up by the supply electrically, this drove the dials, their movement was controlled by two pendulums moving over the coils carrying the supply current, the more current drawn the faster the pendulums would swing, in a circular movement above the coils, this in turn moved the dials . No current at all, no movement.

A0193

MERCURY CONTACT RELAY, 1930's

Switching by contacts immersed in Mercury is almost maintenance free, and can carry reasonable currents.

A0303

RADIOVISOR LIGHT DEPENDANT RESISTOR, 1940's

Light dependant resistor for use in alarm systems or counting in factories.
Resistance of the unit varies with the light shone upon it, so if the light is interrupted the resistance will change.

A0563

WESTERN ELECTRIC GALVANOMETER

Made by the Western Electric Company in America during 1918. A moving coil meter called in this case a Galvanometer, with a full scale deflection of 20 Milliamp s, today it would be called just a moving coil meter. The movement is made by WECO (Western Electric Company) and the horseshoe magnet made by Weston Electric Company.

Nortel Collection

A1355

CAMBRIDGE UNIPIVOT GALVANOMETER, 1920's

Based on Jacques Arsène D'Arsonval's moving coil galvanometer, manufactured on a large scale by the Weston Electrical Instrument Company of Newark, New Jersey, Robert William Paul (1869-l943) devised an instrument in which the moving parts were supported on a single bearing giving lower friction and therefore greater sensitivity. Other unipivot instruments followed. His instruments gained international recognition, winning gold medals at the 1904 St Louis Exposition and the 1910 Brussels Exhibition. In November 1919, his business was bought by the Cambridge Scientific Instrument Company, which was renamed "The Cambridge and Paul Instrument Company." Cambridge Scientific Instrument Company was a company founded in 1881 by Horace Darwin (1851-1928) and Albert George Dew-Smith (1848-1903) to manufacture scientific instruments. Their partnership became a Limited Liability Company in 1895. In 1920 it took over the R.W. Paul Instrument Company of London, and became The Cambridge and Paul Instrument Company Ltd. The name was shortened to the Cambridge Instrument Company Ltd. in 1924 when it was converted to a Public limited company. The company was finally taken over by the George Kent Group in 1968, forming the largest independent British manufacturer of industrial instruments.

A1333

CAMBELL No 106 MIRROR GALVANOMETER, 1912

Mirror galvanometers were used extensively in scientific instruments before reliable, stable electronic amplifiers were available. The most common uses were as recording equipment for seismometers and submarine cables used for telegraphy.
The mirror galvanometer was later improved by William Thomson, later to become Lord Kelvin. He would patent the device in 1858.

Thomson reacted to the need for an instrument that could indicate with sensibility all the variations of the current in a long cable. This instrument was far more sensitive than any which preceded it, enabling the detection of the slightest defect in the core of a cable during its manufacture and submersion. Moreover, it proved the best apparatus for receiving messages through a long cable.

A0191

PHILIP HARRIS MIRROR GALVANOMETER, 1950's

A mirror is hung on a gold thread between an electromagnet, the mirror moves according to current in the coil. A light is reflected of the mirror onto a distant scale amplifying the reading. Used for measuring small electrical currents by amplifying the movement of an armature with a mirror attached to it suspended between a coil. A light is shone onto the the mirror and reflected onto a scale some distance away.

A mirror galvanometer is a mechanical meter that senses electric current, except that instead of moving a needle, it moves a mirror. The mirror reflects a beam of light, which projects onto a meter, and acts as a long, weightless, massless pointer. In 1826, Johann Christian Poggendorff developed the mirror galvanometer for detecting electric currents. The apparatus is also known as a spot galvanometer after the spot of light produced in some models.

A0202

GRIMSDELL DIX TANGENT GALVANOMETER, 1900's

Tangent galvanometer made by Grimsdell Dix Acton London..A tangent galvanometer is an early measuring instrument used for the measurement of electric current. It works by using a compass needle to compare a magnetic field generated by the unknown current to the magnetic field of the Earth. It gets its name from its operating principle, the tangent law of magnetism, which states that the tangent of the angle a compass needle makes is proportional to the ratio of the strengths of the two perpendicular magnetic fields. It was first described by Claude Servais Mathias Pouillet in 1837.

A0192

ADAM HILGER MIRROR GALVANOMETER WITH VIEWING SCREEN, 1950's

A mirror galvanometer is a mechanical meter that senses electric current, except that instead of moving a needle, it moves a mirror. The mirror reflects a beam of light, which projects onto a meter, and acts as a long, weightless, massless pointer. In 1826, Johann Christian Poggendorff developed the mirror galvanometer for detecting electric currents. The apparatus is also known as a spot galvanometer after the spot of light produced in some models.

A0913

CAMBRIDGE INSTRUMENTS MIRROR GALVANOMETER, 1950's

Mirror Galvanometer standard design of the period

A0880

W G PYE CO LTD TANGENT GALVANOMETER, 1900's

If a small current is put through the coil, the compass needle will deflect in a manner dictated by the direction of the current, by this means measurements of small currents can be made.

A0754

PHILIP HARRIS TANGENT GALVANOMETER, 1900's

Used for measuring very small currents of electricity which when passed through the coil would deviate the needle from the magnetic north.

A0258

OERTLING SCIENTIFIC BALANCE, 1950's

By means of a prism and viewing screen, illuminated by a torch bulb, the miniture scale can be read accurately.
Air dampers in brass cylinders are used to stabilise the movement.

A0125

PHILIP HARRIS SCALES, 1950's

Simple version of scales used in Laboratories and workshops.

A0124

OERTLING PRECISION BALANCE, 1970's

Model 142 Scientific Scales used by Chemists and Laboratories.

A1043

TESLA COIL, 1950's

The Tesla Coil was originally designed by Nicola Tesla in 1891 to produce very high voltages. His theories eventually lead to a possible means of transmitting power via a large aerial, replacing power lines, although the first aerial was made in America it never became a practicality. This is a model made for classrooms.

A1022

GRIFFIN AND GEORGE RUHMKROFF INDUCTION COIL, 1950's

In 1857, after examining a greatly improved version made by an American inventor, Edward Samuel Ritchie, Ruhmkorff improved his design (as did other engineers), using glass insulation and other innovations to allow the production of sparks more than 30 centimetres long.
Ruhmkorff patented the first version of his induction coil in 1851, and its success was such that in 1858 he was awarded a 50,000-franc prize by Napoleon III for the most important discovery in the application of electricity.
He died in Paris in 1877.

Bruce Hammond Collection

A1156

PHILIP HARRIS RUHMKORFF INDUCTION COIL, 1950's

Shown working, with the 6 inch spark.

Heinrich Daniel Ruhmkorff (January 15, 1803 in Hanover – December 20, 1877 in Paris) was a German instrument maker who commercialised the induction coil (often referred to as the Ruhmkorff coil.)
Ruhmkorff was born in Hanover. After an apprenticeship with a German mechanic, he moved to England. Biographies say that he worked with the inventor Joseph Bramah, but this is unlikely since Bramah died in 1814. He may, though, have worked for the Bramah company.
In 1855, he set up a shop in Paris, where he gained a reputation for the high quality of his electrical apparatus.

A0947

UEREKA 6 INCH RUHMKORFF INDUCTION COIL, 1950's

Electromagnetic induction was discovered by Michael Faraday (1791-1867).
In 1831 Nicolas Callan (1799-1864) invented the Induction coil.
In 1836 they were used for medical complaints such as skin disorders, and to power X ray machines.
Marconi used one for his transmitter system at Poldhu in Cornwall for the first transatlantic transmission.
Later coils such as this unit, were made for schools and Colleges as demonstration units.

A0135

5 INCH INDUCTION COIL, 1950's

In several of Jules Verne's science-fiction novels, so-called "Ruhmkorff lamps" are mentioned. These were an early form of portable electric lamp. The lamp consisted of a Geissler tube that was powered by a battery-powered Ruhmkorff induction coil, an example of one (made much later)is shown here.

A0966

LECLANCHE CELL, 1896

The cell was invented by Georges Leclanche' in 1866, it is the forerunner of modern Zinc Carbon dry cells. In the centre is a porous cylinder filled with Manganese Dioxide and in the centre of this is a carbon rod. Outside of the cylinder is a zinc rod. The jar would normally be filled with Ammonium Chloride. The negative terminal is the carbon rod and the zinc is positive. The voltage obtained is 1.5 Volts.

Georges Leclanché (1839 - 1882) was a French electrical engineer chiefly remembered for his invention of the Leclanché cell; one of the first modern electrical batteries and the forerunner of the modern dry cell battery.
The original form of the cell used a porous pot. This gave it a relatively high internal resistance and various modifications were made to reduce it. These included the "Agglomerate block cell" and the "Sack cell".

A0186

GRENET CELL, 1888

The power source used by Thomas Edison with his original Phonograph, invented by the German Johan Christian Poggendorff (1796-1877). Called Grenet Cell because he made a practical version possible. Used as a source of power before the Dry Battery became available. It consists of three plates in a jar filled with 17 parts potassium dichromate dissolved in 100 parts of distilled water with the addition of 22 parts sulphuric acid. The two positive plates are made of retort graphite, the negative Zinc that can be raised or lowered into the solution; this prevents corrosion when not in use. These units come in varying sizes from 1/3 to 3 Litres.

A0185

ELECTROSCOPE, 1900's

The Electroscope was used for the the detection of electrostatic charges. If a charged item, (such as an Ebonite rod that has been rubbed) is held near the the brass terminal, the gold leaf will deflect away from the mounting.

A0259

TANDY 160 IN ONE, 1960's

Hobby kit for children and adults to learn electronics. A popular pastime from the 1900's to the 1970's. A version of this equipment can still be found today, and is still used as a teaching aid.

A0104

MICROSCOPE, 1900's

Simple brass microscope, still in excellent working order, the wooden box is very basic.

A0126

6 GRIFFIN AND TATLOCK VACUUM TUBES IN A RACK, 1950's

The Cross vacuum scale demonstrates the phenomenon of discharge at different pressures. The pressure in the tubes varies between 40 Torr (mm/Hg), the lowest vacuum in the left tube, to 0.03 Torr the highest vacuum in the right tube.

It is in this high vacuum, used in many Crookes tubes, that X-Ray's are produced.

A0948

ABSORBIOMETER, 1940's

A spectrometer is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization state.

A0915

PHOTO ELECTRIC ABSORBIOMETER, 1950's

Using the 'Spekker' Principal and used for the analasys of Iron. A known sample is placed on one side of the lamp, and the specimin on the other. Filters are added, and the refraction of light is used to measure the unknown sample against the known one, using a Galvanometer. This Field of research is associated with Spectometry

A0912

MAGNET, 1960's

Could have been used in experiments on Magnatrons.

A0946

PHILIP HARRIS ELECTROSCOPE, 1890's

Used for the the detection of electrostatic charges. If a charged item such as a Ebonite rod that has been rubbed is held near the the brass terminal, the gold leaf will deflect away from the mounting.

Bruce Hammond Collection

A1148

GEISSLER TUBES

One tube Marked 6132 for Helium. One Marked 6130 for Nitrogen. The others marked Oxegen Hydrogen and Carbon Dioxide. Heinrich Geissler (1814-1879) The Geissler tube is a glass tube for demonstrating the principles of electrical glow discharge. The tube was invented by the German physicist and glassblower Heinrich Geissler in 1857. The Geissler tube was an evacuated glass cylinder with an electrode at each end, it would contain one or more of the following rarefied (thinned) gasses, such as neon, argon, or air, mercury or other conductive liquids, or ionizable minerals or metals, such as sodium. When a high voltage is applied to the terminals, an electrical current flows through the tube. The current will disassociate electrons from the gas molecules, creating ions, and when electrons recombine with the ions, different lighting effects are created. The light will be characteristic of the material contained within the tube and will be composed of one or more narrow spectral lines. The museum has several Geissler Tubes which can be demonstrated.

A0969

5 X GEISSLER TUBES, 1950's

Illuminated

A0969

CROOKES TUBE, 1950's

Used in class rooms to demonstrate high voltage effects on evacuated tubes,or Cathode Rays. Sir William Crookes circa 1875. (1832-1919) The Railway tube or Paddle Wheel demonstrates Kinetic Energy.
The electrons bounced at the paddles (which are covered
with a small amount of a Mineral which will glow for effect), this will turn
the paddle wheel and move from one end of the tube to the other.
Crookes thought that Cathode Rays had momentum, but in 1903 J.J.Thomson proved that the rays hitting the paddle heated the gas on that side causing it to expand, as the gas on the other side remained cool, the vane moved away from the ray.
The railway tube was one of the models
Crookes demonstrated in his famous lecture in
Sheffield 1879.

A0264

CROOKES TUBE, 1950's

Illuminated

A0264

CROOKES TUBE "MALTESE CROSS", 1950's

Used to demonstrate cathode rays. A negative voltage is connected to the small end and a positive connected to the cross. The tube is evacuated of air, and when the voltage is applied, electrons (cathode rays) travel from the small electrode towards the cross, some hit the cross while others carry on and illuminate the end of the tube leaving a well defined shadow. This was the first cathode ray tube, probably attributed to Johann Wilhelm Hittorf in 1869, the same period as Crookes was experimenting.

A0265

MALTESE CROSS, 1950's

Iluminated

A0265

CROOKES TUBE, 1950's

Used to demonstrate the effects of high voltage on liquids and gases in Schools and Universities. The yellow area is a liquid called Flourescene, two other elements are provided producing three colours in all, which glow yellow, green and violet, when hit by electrons created by a very high voltage

A0883

CROOKES TUBE, 1950's

Illuminated

A0883

GEISSLER TUBE, 1950's

Geissler tubes, were named after the man who first devised them (1814-1879), to demonstrate the effect of high voltages on different gases or air that has been rarefied. This one would have been made for a University or College. The Geissler tube is a glass tube for demonstrating the principles of electrical glow discharge. The tube was invented by the German physicist and glassblower Heinrich Geissler in 1857. The Geissler tube was an evacuated glass cylinder with an electrode at each end. A Geissler tube contains one or more of the following rarefied (thinned) gasses, such as neon, argon, or air; mercury or other conductive liquids. When a high voltage is applied to the terminals, an electrical current flows through the tube. The current will disassociate electrons from the gas molecules, creating ions, and when electrons recombine with the ions, different lighting effects are created. The light will be characteristic of the material contained within the tube and will be composed of one or more narrow spectral lines.

A0851

GEISSLER TUBE, 1950's

Illuminated

A0851

CROOKES TUBE WITH BUTTERFLY, 1900's

Used in class rooms to demonstrate high voltage effects on evacuated tubes and Chemicals. The butterfly is made of metal, coated in different minerals, when the electrons hit the elements they glow in the associated colour for that type. The principal is similar to a modern fluorescent tube. We can demonstrate this item in the museum along with a number of other electrical objects.

A1135

CROOKES TUBE WITH BUTTERFLY, 1900's

Illuminated

A1135

WHIMSHURST MACHINE, 1890's

This electrostatic device was invented between 1880-1883 by British inventor James Wimshurst. It was used for generating high voltages, the machines were frequently used to power X Ray tubes.

The Wimshurst Machine belonged to a class of generators called influence machines, they separated electric charges through electrostatic induction or influence.

The Wimshurst Machine is self-starting, meaning it doesn’t need external electrical energy, it does however, need mechanical power and by turning the handle very quickly the two glass disks and their metal sectors rotate in opposite directions passing the crossed metal neutraliser bars and their brushes.

An imbalance of charges is induced, amplified and collected by two pairs of metal combs with points placed near the surfaces of each disk, this creates a spark, and the accumulated energy can be collected and stored in the two “Leyden Jars”

Bruce Hammond Collection

A1153

WIMSHURST GENERATOR, 1950's

Wimshurst built these machines between 1880 and 1883.

This unit was used in schools and colleges up to the early 1980's and is not antique although they are now seldom seen. It was used as a training aid in a subject that is no longer considered important in a world of computers.

The two disks rotate in opposite directions when the handle is turned. Strips of foil on the disks are rubbed with two wire brushes, static is picked up by prongs positioned close to the disks and stored in two jars (Leyden Jars). When the charge is sufficient a large spark discharges the stored energy across a gap by two brass rods.

A0114

SIEMENS ELECTRODYNAMOMETER of 1881

An early current meter was the electrodynamometer of 1881.
It was used until the 1920s when it was replaced by the direct reading meter patented by Edward Weston.
The basic principle was laid out in an 1848 paper by Wilhelm Weber (1804-1891)


Used in the early 20th century, the Siemens electrodynamometer, for example, is a form of an electrodynamic ammeter, it has a fixed coil which is surrounded by another coil having its axis at right angles to that of the fixed coil. This second coil is suspended by a number of silk fibres, and to the coil is also attached a spiral spring the other end of which is fastened to a torsion head. If the torsion head is twisted, the suspended coil experiences a torque and is displaced through and angle equal to that of the torsion head.



Bruce Hammond Collection

A1205

WESTON ELECTRIC METER, 1930's

In 1886 Edward Weston developed a practical precision, direct reading, portable instrument to accurately measure electrical current, a device which became the basis for the voltmeter, ammeter and watt meter. This model dates from the 1930's

Nortel Collection

A1348

UNIPIVOT METER, 1930's

In 1903 Paul introduced a new design of galvanometer, the ‘Unipivot’ galvanometer. It was a robust, easy-to-use, pivoted moving-coil instrument, more sensitive than previous instruments of this type and superior to the widely used moving-magnet instruments. This Instrument dates from the 1930's

Nortel Collection

A1347

AVO MODEL 7 MULTIMETER, 1950

The model 7 was intended more for electricians and power engineers. The model 8 was better for bench electronic engineers. These meters were the classic instrument for test engineers in the radio and TV service industry for many years.

A1331

AVO MODEL 40 MULTIMETER, 1964

This classic Avometer was introduced in 1939. At 333 Ohms-per-volt not designed for electronic equipment. It was advertised as a 'Power Engineer's' meter. Introduced in 1939 and initially supplied to the Admiralty.

A1332

ADVANCE SIGNAL GENERATOR TYPE E MODEL 2, 1949

Well Known Signal Generator used by the Trustees, and in Radio and Telivision workshops for aligning Radio's and early Televisions during the 1950/60's. Covers 100Kc/s to 100Mc/s in six ranges , Band A : 100 - 300Kc/s
Band B : 300 - 1000Kc/s
Band C : 1 - 3 Mc/s
Band D : 3 - 10 Mc/s
Band E : 10 - 30 Mc/s
Band F : 30 - 100 Mc/s The manufacturers claim it had an accuracy of +/- of 1% over the whole range

A1342

TINSLEY CHART RECORDER, 1950's

Chart Recorder with Indian ink type pen, used for measuring current, and driven by a 220vac motor.

A0158

AVODAPTER VALVE TESTER ADAPTERS, 1932

The units are plugged into a receiver between the valve under test, the set is switched on and after a warm up period with the leads connected to a test meter the performance of the valve can be measured.
The four and five pin unit in 1923 cost 25 Shillings and the seven pin unit cost twelve shillings and six pence.

Bruce Hammond Collection

A1263

EPSYLON TRAINER RADIATION METER No1, 1950's

The unit is not very sensitive,and the scale is not calibrated, the word trainer indicates its nature.
This is a companion model, the trainer is used to teach the use of the Radiac Model No2. Item A1300.
The range is low so it will detect the weak training sources used to simulate radioactive fallout.
See Radiac No2, A1300 for more information.

A1299

POST WAR POCKET DOSIMETER, 1950's

A radiation dosimeter is a pen-like device that measures the cumulative dose of radiation received by the device. It is usually clipped to clothing to measure the actual exposure to radiation.
Magnifying lenses (a low-power microscope) and an illumination lens, helps to read the dose by aiming the illumination lens at a light source and looking into the device.

For personal use, this is the most useful device to measure radiation, because biological damage from radiation is cumulative.

Dosimeters must be periodically recharged. The dosimeter is usually read before it is charged, and the dose is logged, to chart exposure.
In many organizations, possession of the recharger is limited to health physicists to prevent falsification of exposures.

A0515

No 1 POST WAR CONTAMINATION DETECTION METER, 1954

Radioactivity detection unit, produced after the Second World War as a result of the Cold War period. These units were made on instruction from the government, and supplied to all Councils and Military establishments.
It was expected that in the event of a Nuclear attack, they would be ready to measure contamination levels.

A0513

CONTAMINATION LIQUID HEAD DETECTOR, 1950's

Spare detector head for the contamination meter Item A0513.
For reading liquids

A0514

RUSSIAN POCKET DOSIMETER AND CHARGER, 1950's

Four pocket Dosimeters and charger unit, inside a Bakelite Case.
Used for detection of radiation.
This item was made in Russia

A0979

EK COLE METER SURVEY RADIAC No 2 RADIATION METER, 1955

The scale is not calibrated, The range switch has 4 positions 0 - 3 r/hr / Scale Indicator White (shown)
0 - 30 r/hr / Scale Indicator Blue
0 - 300 r/hr / Scale Indicator Red
Set Zero / White Scale Indicator
The meter can be read while in the carry case and a side flap opens to allow access to the controls.
Measures Gamma - Detects Beta
Beta detection is accomplished by removing the base plate and a barrier plate inside. The unit was used by the Civil Defence Post War. Although referred to as Geiger counters, most CD devices were radiological survey meters capable of measuring only high levels of radiation that would be present after a nuclear event. Required 2X 1.5Volt 1X 9Volt and 1X 30Volt Batteries. The Radiac Survey Meter No 2 or RSM was a 1955 meter which counted the particles produced by radioactive decay. This meter suffered from a number of disadvantages: it required three different types of obsolete batteries, it also contained delicate valves that were liable to failure and it had to be operated from outside the protection of the post.
These were favoured as they had been tested on fallout in Australia after the Operation Buffalo nuclear tests, and remained in use until 1982 by commissioning a manufacturer to regularly produce special production runs of the obsolete batteries.

A1300

DOSIMETER GEIGER COUNTER, 1970's

Found in Belgrade and ended up in the UK
Measures down to point 01 of a Roentgen.

A1294

EKCO BETA/GAMMA DOSE RATE METER Type 95/0030, 1970

Unit used for measuring the strength of radiation over time, not suitable for contamination measurements, this unit will measure the amount of radiation that will be absorbed by coming into contact with the material on test, over one hour. The strength of the object on test is read in Roentgen/Hours, this means that although coming into contact with the object will cause absorption of radiation immediately, its seriousness is only measured if the contact is sustained over a period of time.

A1357

THEODOLITE DIRECTOR No5 MK1, 1916

Theodolite dated 1916 with broad arrow indicating it has been adopted for military use.

A1134

LARM-U FIRE DETECTOR, 1930's

Early Fire detector using a small plastic disk tensioned by a spring, temperatures above habitable conditions will soften the plastic forcing the steel disks together, creating a circuit which could ring a bell or bells.

A0314

CASSELLA AIR FLOW METER, 1960's

Meter used for measuring air flow Velocity 200-3000 No L 11434

A1020

DOMESTIC POWER METER BY SIEMENS LTD, 1930's

Plugged into a lamp socket, the appliance was plugged into the meter ,it then measured the current being drawn.
Used in the days when household power points were rare if not non existent, and electric irons were plugged into the light fitting.

A0282

EARLY THERMOSTAT, 1930's

Thermostat for a variety of uses.
May have been made for a specific piece of equipment.

A0308

EARLY THERMOSTAT, 1930's

Early type thermostat using a sealed atmospheric chamber and a very strong spring.
A lever tilts a Mercury switch

A1013

VOLT AND AMP METERS, 1930's

Repair departments measuring meters before multi meters became available.
Volt meter is 0 to 10 volts
Amp meter is .5 To 3 amps.

Bruce Hammond Collection

A1191

EARLY MOVING COIL METER, 1900's

Early moving coil meter in wooden box with wall fixing or stand alone on two adjustable feet.

Bruce Hammond Collection

A1210

KELVIN AND WHEATSTONE BRIDGE, 1948

Used for measuring an unknown resistance.
The Kelvin portion enables reading accurately very low resistance (below 1 Ohm). The Kelvin Bridge makes allowances for the high currents used for measuring very low resistances, as heat generated can cause errors.

A1128

HYDROMETER FOR WHISKY BY SIKES, 1960's

Used for measuring the specific gravity of Whisky.

A0260

ROUND AMP METER, 1940's

General industrial meter for measuring power sources, with 270 degree scale.

A0128

GEC ROUND VOLT METER, 1940's

General industrial meter for monitoring power sources.

A0127

WATSON KILOVOLT METER, 1940's

0 To 250 kilovolt meter.

A0111

WATSON MILLI AMP METER, 1940's

0 to 20 Milli amp meter.

A0112

NEWTON AND WRIGHT BRASS AMPMETER, 1930's

Surface mounting ampmeter for 0-25 amps in brass case.

A0256

CIRSCALE AMPMETER, 1930's

Meter for measuring direct current up to 300 amps.

A0255

NADIR MULTI METER, 1930's

Forerunner to the modern Multi Meter

A1093

RESISTOR SUBSTITUTION BOX, 1950's

Substitution boxes are used for temporarily replacing resistors that may be assumed faulty, or inserting a known value of resistance into a circuit and conveniently adjusting the value.

A0107

CAMBRIDGE PORTABLE pH METER, 1940

Moisture content measuring device

A1092

HEILAN MOISTURE METER, 1930's

Early equipment for the measurement of moisture

A1094

SHEATH CURRENT TESTER, 1930's

Used by the GPO for measuring underground cable sheath current to detect breaks

A1096

TEKTRONIX OSCILLOSCOPE, 1960's

Large valve type Oscilloscope used in service Laboratory's throughout the world Usually mounted on a steel trolley

A1016

UNIVERSAL AVO MULTIMETER., 1930's

The Universal AVO meter of 1933 Dated 1938. This was the first in the range of these famous instruments, and was replace by the model 40.

Avo Multimeters were the mainstay of the service industry in the 1950's to the 1990's and are still available today, but extremely expensive. The 'Automatic Coil Winder and Electrical Equipment Co.', Douglas Street, London SW1, later renamed to 'AVO Ltd.' (which should not be mixed up with 'Avo International Ltd.)
AVO is well known for it's very solid and reliable measuring instruments, and - coil winding machines.

A0108

AVO MINOR MULTI METER, 1930's

Cheapest of all AVO meters in original case, to change the range you simply re plug the leads.

In 1938 the AVO minor cost 45 Shillings.

A1009

AVO MULTI MINOR MULTI METER, 1930's

AVO is well known for it's very solid and reliable measuring instruments.this unit was less expensive than the larger models, but unlike the Minor had a switch to change the range.

AVO 'Automatic Coil Winder and Electrical Equipment Co'.

A0109

SONIC BOOM DETECTOR, 1950's

Developed as a prototype to measure sound pressure levels to evaluate damage caused by Military Jets flying over buildings.
New Laws regarding Supersonic aircraft flying over built up areas rendered it obsolete.
Similar units are now used to measure explosions.

A1015

GPO ENGINEERS TOOL BAG, 1930's

Standard Issue GPO engineers tool bag of the period.

A0518

SHORTS GAS INDICATOR, 1900's

Used for measuring the coal gas content in air by atmospheric pressure, and indicated by the percentage of coal gas.
The mechanics of the instrument are identical to that of a normal Barometer.

A0323

AVO 160 VALVE TESTER, 1960's

Useful for testing Military valves as well as commercial types. Basically the 'Automatic Coil Winder and Electrical Equipment Co.', Douglas Street, London SW1.
Later renamed to 'AVO Ltd.' (which should not be mixed up with 'Avo International Ltd.)
AVO is well known for it's very solid and reliable measuring instruments, and coil winding machines.

A0103

PIFCO ALL IN ONE METER, 1920's

Meter for home workshops, with 5 ranges and 7 terminals, including a lead from the top centre terminal that is missing on this unit.

A0309

PARA VOLT FOB METER, 1920's

Engineers pocket voltmeter.
The museum is lucky to have the original box.
120 Volts Dc could have been the local mains voltage before 1930.

A0301

POCKET FOB WATCH METER, 1920's

Engineers pocket meter, which looks just like a pocket fob watch.
120 Volts Dc could have been the normal mains voltage before 1930.

A0300

FOB VOLTMETER, 1930's

Pocket meter for engineers.
120 Volts DC could be a normal mains voltage before 1930.

A0299

MANGANIN WIRE RESISTANCE UNIT, 1930's

Manganin was used in the 1930's as a replacement for Nickel Silver used up until then.
Manganin and Ureka wire was superceded by Nickel Copper and Nickel Chrome Alloys.

A0334

CAMBRIDGE POTENTIOMETER 4 DIAL BOX, 1959

Modern Scientific Bridge with accurate voltage reference for measurement of resistance

A0201

THERMASTER LOW TEMPERATURE INDICATOR, 1950's

Unit for measuring temperature from zero to 100 degrees centigrade.
The knob is turned until the needle centres between increase and decrease.
The temperature is read from the scale attached to the knob.

A0212

WESTON NORMALCELL, 1950's

Standard voltage Cell for use with accurate measuring equipment such as the Wheatstone Bridge.

Edward Weston (May 9, 1850 – August 20, 1936) was an English chemist noted for his achievements in electroplating and his development of the electrochemical cell, named the Weston cell, for the voltage standard. Edward Weston was a competitor of Thomas Edison in the early days of electricity generation and distribution.
Weston' son Edward Faraday Weston also received several patents regarding exposure meters.

A0333

GPO EXCHANGE TEST SET 5422, 1960's

Used in exchanges for testing equipment.
Marked DGM ATW 54220 Issue 4

A0044

GPO TEST SET No 36, 1950's

Test equipment used for detecting fractures in under ground lead sheathed cables.

A0030

GPO 37 MIRROR GALVANOMETER, 1954

Galvanometer unit for use with other test gear.
May have originally come from Dollis Hill Laboratories.
And may have been made by H.W.Sullivan Ltd in 1954.

A0076

PO NON REACTIVE SLIDE WIRE AND BOX, 1920's

This piece of equipment is in excellent condition and may have come from Dollis Hill Laboratories.

A0077

GPO 74101D OSCILLATOR, 1950's

This too may have come from the Dollis Hill Laboratories.

A0075

GPO 74101 TRANSMISSION TEST SET, 1950's

Originally may have come from Dollis Hill Laboratories.

A0074

WESTON ELECTRIC METERS, 1918

The calibration certificate for the ammeter is for Serial No 30940 ?
The meter shown is Serial No 23602.
The Voltmeter is dated 13 Jan 1920.

British-born American electrical who revolutionized the Electro-plating industry, founded the Weston Electrical Instrument Company. A prolific inventor who held 334 patents, Edward Weston May 9, 1850 – August 20, 1936 helped revolutionize the measurement of electricity.

Weston' son Edward Faraday Weston also received several patents regarding exposure meters.

A0975

LEEDS AND NORTHRUP SPEEDOMAX "H" CHART RECORDER, 1960's

Valve chart recorder, for measuring and recording on paper information collected by sensors sensitive to voltage or current readings, meaning it could record almost any equipment with a sensor attached to it.

A0957

LAFAYETTE MULTIMETER, 1960's

Amateur large scale multi meter, from the 1960's. Uses obsolete battery for high resistance measurement.

A0956

CAMBRIDGE RESISTANCE BRIDGE CALENDAR & GRIFFITHS, 1887

Resistance Bridge (Collins Patent) with pots normally containing a liquid, using pegs, which when dipped, creates a switch.
Messrs Calendar and Griffith invented their Bridge in 1878, it went on to be used well into the 1930's.

A0976

PO RESISTANCE BANK 375, 1940's

Used by G.P.O. engineers as a reference for resistance measurement.
Type 375

A0942

RADIATION METER/ PORTABLE ELECTROMETER, 1950's

Used to test for radiation leakages on X- Ray equipment.

A0117

GLUCK BAROGRAPH, 1960's

Modern example of air pressure measuring instrument in original style case.

A0161

MUIRHEAD D-972-A POTENTIOMETER , 1960's

Direct Current measuring device used for accurate measurement of voltages. all voltage measurements are referenced from a 'Standard Cell' similar to Item A0333.

A0882

CABLE TENSION METER, 1960's

Used by aerial cable engineers, such as the Post Office for telephone and telegraph lines, for tensioning the cable correctly.

A0276

ENGINEERS CLINOMETER, 1940's

Used by engineers for checking gradients on structures.

A0275

RADAR KILOVOLTER HIGH VOLTAGE METER, 1950's

For measuring high voltages, probably a TV tubes high tension, the probe on the left is held on the voltage output to be tested, after the lead is connected to ground.
By adjusting the knob on the right the distance between the two balls is reduced untill the voltage sparks accross the gap, the voltage is then read from the scale.

A0274

WAR DEPARTMENT WHEATSTONE BRIDGE, 1940's

War Department Wheatstone Bridge for the accurate measurement of resistance.
Similar to the Post Office standard Wheatstone Bridge.

A0330

WAR DEPARTMENT RESISTANCE BRIDGE, 1915

Together with a Galvanometer and a standard voltage cell Like Item A0333, clipped into the pillars on the right of the instrument, accurate readings of long lines could be measured.
Can be been wired in a bridge configuration.

A0332

TELEGRAPH BRIDGE AND INSULATION TESTER, 1940's

Bridge and insulation tester used in telephone and telegraphy workshops.
Complete with Tangent Galvanometer.

A0331

LOGOHM MK 6 RESISTANCE BRIDGE, 1940's

A battery operated resistance meter operated in a bridge configuration i,e, with three known resistance it is possible to identify the missing section of the circuit when all components are connected in a circle or bridge configuration. Sets like this were made by many manufacturers in the UK before mass production from Japan and China took over.

A0744

WR MORRIS HOT WIRE AMMETER, 1930's

Hot Wire Ammeters work the expansion and contraction of a piece of wire when heated by an electric current. Although not very accurate and prone to ageing effects of the wire, they were an inexpensive way of indicating currents of over 100 Milliamps.
Smaller current versions would have made the wire too fragile.

A0722

DC4 VALVE AMPLIFIER, 1950's

Laboratory Volt meter with valve amplification providing a very high input resistance.

A0740

GPO EVERTSHED AND VIGNOLES MEGGER, 1923

Megger instrument for measuring very high resistances (leakages), using high voltages created by winding the handle on the end.
Used by the GPO on Telephone lines.

A0582

SURVEYORS TROUGH COMPASS IN BOX, 1970's

Surveyors compass's, which have a needle with small sideways movements and few degree marks. Designed to be small and portable, would be used with maps on site.

A0715a A0715b

MAGNETOMETER, 1900's

Also called a Gaussmeter, after Carl Friedrich Gauss in 1833. It measures the direction and strength of magnetic fields in the vicinity of other affecting objects.

The earth's magnetic field (the Magnetosphere) varies due to influences of rocks and ores in the ground or the interaction between particles from the sun affecting the Magnetosphere. This is an early instrument for measuring these effects. It could be mounted on a long rod and slid along taking readings at precise intervals.

A0257

SHARMAN PIPE OR CABLE FAULT LOCATOR, 1914

Patents 16799 15th July 1914 and 24056 15th Dec 1914 accredited this item to Alexander William Sharman, holder of 40 other electrical and scientific patents.

A transformer like search probe for locating breaks in metal pipes and cables which would be connected to the oscillator output (red lead) while the negative lead is connected to a metal stake which is driven into the ground to provide a return circuit. Headphones can be connected to the search probe or to the accessory search coil.

A0204