29 CATHETOMETER (c.1960)
Scientific Pye Instruments / Serial No. 67 662 / WG Pye & Co / Gratuta Works, Cambridge
Round section column engraved in mm, to 1020 mm, carrying a telescope having 20 mm aperture and x10 magnification, focusing from infinity to approx. 60 cm, having fine pitch screw for leveling and horizontal bubble level. Telescope carriage locked by one sleeve on main column. Fine adjustment is obtained by clamping the telescope carriage to a second rod, being raised or lowered by means of a micrometer screw fine adjustment, which reads to 0.05 mm. Attached magnifying lens is used to give accurate readings from scaled column.
The main column and guide rods are supported by semi-kinematic mounts with the column mounted between heavy cast end plates on three screw-thread adjustable fee having 2 bubble levels in base arms.
Such devices are used to measure small changes in height of substances or objects at reasonable proximity to the instrument. The micrometer allows fine scale adjustment of height of the telescope carriage and hence small variations in the levels of fluids in a column or extension or contraction of objects may be gauged.
35 BEAM BALANCE
Sartorius-Werke, Gottingen, Germany, (c.1950)
Chemical balance in a polished wood case, glass windows on all four sides. Front window is counterpoised and the side windows can be pulled back. Case has two leveling screws and one bubble level. External weights are required. Vemier is attached to permit fine readings down to 0.1 mg. For 100 g weight can discriminate to 1 part in a million.
Both arms are divided into 10 major equal parts, subdivided again into a total of 100 parts. The rigid beam carries steel knifes that turn on an agate plate. On both ends of the moving arm, light aluminium pistons are attached allowing for pneumatic damping. These pistons oppose any rapid motion of the beam. Retarding effect decreases to zero as the arm comes to rest. In order to make fine readings a 10 mg rider is used. The rider placed at the reading main divisions will have the same turning effect as weights to a total of milligrams that are placed on the pans.
167 GRAVITY BOTTLES
Wooden box containing 27 specific gravity bottles.
Sealed pear-shaped glass bottles. Bottles are 2.5 cm in diameter at the widest point and 8.5 cm in length from bulb containing a mercury droplet to the moulded hook at top.
Specific gravity bottles used to measure the density of liquids relative to the density of water (Specific gravity H2O = 1). Twenty seven bottles containing finite amount of mercury are graduated by 0.05 divisions from 0.70 to 2.00. The bottles were donated by the X-ray and Radium Laboratory at The University of Queensland , however they were only used there once in ultra-violet light experiments. Gravity bottles can be used to measure the changing effects of temperature on the density of water. Electromagnetic radiation absorbed by water raises the temperature and decreases the density.
Bottles suspended by hook with string or wire in water or other liquid will sink or float depending on the relative density of the fluid. For changes in temperature of water due to radiation source several bottles can be floated. The density when each bottle begins to sink can be correlated to the temperature change, a technique going back to Galileo.
Solmon Marks and Co, Cardiff
Brass sextant with wooden handle and finely engraved silver scale. The mirrors and filters are present but the telescope is missing.
Light from a celestial body such as the Sun or a star is reflected by a mirror attached to a moveable arm, through a mirror which also allows the horizon to be sighted simultaneously.
By bringing the image into coincidence with the visible horizon it is possible to measure the elevation of the body. Using an almanac and an accurate clock it is then possible to determine the position of the observer on the Earth's surface. This was the standard method of navigation from about 1800 until about 1980.
59 BUBBLE SEXTANT MARK IXA
A.M. Bubble Sextant Mark IXA Ref. No. 6B/218, Ser.No. 10651/42(v)
Black japanned metal case with rubber rimmed eyepiece at back and open slot at front where a black drum houses the clockwork automatic averaging attachment. The left half of the sextant carries the bubble and its collimating system, which together form the artificial horizon, while the right half carries the sextant proper: the mirrors and filters and angle scales. Lamps are provided for night observations.
A normal sextant is unsuitable for use in an aircraft because the horizon is not level with the observer as in a ship, so the bubble sextant was developed for aeronautical use in the 1920s.It was very important in WWII. The automatic averaging atachment was meant to ensure that unbiassed measurements were made while the bubble and observer wobbled randomly, so that the error would reduce as the square root of the number of observations. Sixty measurements were averaged as the observer tried to keep the bubble and a star in coincidence for a two minute period.
image a image b image c image d image e
A circular steel rim, 5 cm wide and 1 cm high, with three identical spike-shaped legs at equal 120° angles, beneath. A central support with inset screw thread, forming a similar spike of variable height. A rotating disk fixed horizontally to the circular rim, with gradations to measure the height of the disk.
Used to measure the radius of curvature of an extended object, for example a lens, to reasonable precision. The vertical scale is used as a height measurement for the screw (with the disk as a marker), and the graduations on the disk as a fine-resolution device for the same measurement, to fractions of a revolution. Adjustment of the screw to place all four legs on the surface, allows calculation of the radius of curvature from the height measurement and the dimensions of the device.
171 ASHDOWN ROTOSCOPE
A.J.Ashdown Ltd., London
A patented shutter controlled by a gear connected to a centrifugal governor. A winding rod fits under the bottom handle to wind a spring. The speed of the gear is controlled by 5 sliding gear -coarse settings and an infinite graduation control achieved by a balanced centrifugal governor.
The Ashdown Rotoscope acts to gear human vision up to zero speed relative to an object having recurrent motion. A shutter turns at an accurate speed only allowing the viewer to see at instants certain time intervals apart. If the object under test executed a recurrent motion, then it is possible to view the object as stationary, or nearly so, by adjusting the time interval accordingly. The governor can be made to run between 50 and 125 RPM and thus by multiplying this with the gear ratio, the shutter speed may be calculated. The Rotoscope was used in two ways:
25 CHRONOMETER, ELECTRIC WIND
(Mercer' Repeater Contact Clock MS 152)
Thomas Mercer Ltd., St. Albans, England, (1956)
Wooden case contains electrically rewound chronometer with 1s contacts and repeater dial mounted on door. The repeater movement consists of an electromagnet which, when energised by a current impulse from the master clock, causes an armature to close and a pawl to advance a feed wheel one tooth. A train of gears from the feed wheel spindle drives the hands .
The master clock has a heavy balance wheel and helical balance spring and a spring detent chronometer escapement. Each second a pair of contacts closes and a current pulse is sent to the repeater movement. The driving spring is normally rewound at regular intervals by an electromagnet but can run for up to four hours if the supply is interrupted.
Such clocks were used to control dials in the public areas of ocean liners. This one was used for accurate timing of radio propagation experiments carried out at Mt. Nebo and Everton Park.
27 PENDULUM MASTER CLOCK
SYNCHRONOME ELECTRICAL COMPANY OF AUSTRALASIA, BRISBANE
Grey painted wooden case with glazed door. Lower dial with hour and minute hands and seconds bit and. upper dial with sweep seconds hand only mounted on inside of door. Black japanned casting carries pendulum, countwheel, gravity arm and solenoids.. Subsidiary seconds counter fitted.
Electrically reset gravity escapement. With each swing of the seconds pendulum, the countwheel is advanced one tooth. Each half minute, a detent is tripped and an L-shaped lever falls down. It carries a roller which impulses a specially shaped arm attached to the pendulum, keeping it in motion. The other arm of the lever makes a contact which energises the solenoids . These pull in an armature which resets the lever ready for the next half-minute impulse. The same current also flows to the solenoids operating the dial(s). As this moves the hands only twice a minute, a subsidiary seconds counter, which provides an impulse at each swing of the pendulum, has been fitted to this clock which was used to time and control ionospheric observations at the Moggil field station, starting in the International Geophysical Year in 1958.
Synchronome pendulum clocks were also widely used in the University to operate slave dials in lecture rooms and to control bells and timers.
124 SUBSTANDARD METRE (c 1910)
Made by the Societe Genevoise, Geneva for the Cambridge Scientific Instrument Co
176 Invar Coulee 1833 No 12214
The Invar substandard metre is contained within its own box and has a cross-section which looks like: H The bar is marked off in millimetres, with every tenth one enumerated. The last (1000th) millimetre has ten fine subdivisions. A travelling microscope would have been used to make measurements with the substandard metre. Preserved in each country was a standard metre against which the substandards were compared.
Invar is a nickel-steel alloy (35.6% nickel) with an extremely low coefficient of thermal expansion. It was invented in 1890 by the Swiss Charles-Edouard Guillaume (1861-1938) whilst working for the International Bureau of Weights and measures in Paris. Guillaume received the Nobel Prize for Physics in 1920 for his work with nickel-steel alloys.
The metric system came into being in France in the 1790s. The metre was originally defined as 10-7 of the Earth's quadrant (passing through Paris) and the first standards were platinum. During the nineteenth century, the metric system was gradually embraced by nations world-wide. In 1960 the metre was redefined in terms of the wavelength of the orange-red line in the krypton-86 spectrum and more recently as the distance travelled by light in vacuum in a certain number of oscillations of a Cs clock.
30 McLEOD GAUGE
W. Edwards & Co. Ltd., London
Lacquered wooden upright stand supporting vacuum tubes and compression bulb. Mounted below the assembly, a moveable metal weight, acting as a plunger. The McLeod gauge is a form of mercury manometer adapted for the measurement of pressures in the 1 - 10-3 Torr range.
To make a pressure measurement, the weight is lowered emptying the compression bulb. Connecting the vacuum system to the gauge, the weight is then raised filling the compression bulb with mercury, first trapping the gas contained within it and compressing in into the capillary tube. This effectively amplifies the system pressure. Knowledge of the bulb volume and capillary diameter allows a direct calibration.
294 MERCURY FORTIN BAROMETER
Griffin, London 2195 (c1920)
A wooden wall plaque supports a brass outer casing which protects the glass barometer tube and wood and leather cistern. A brass screw provides the means to raise or lower the level of mercury in the cistern to a fiducial point in the form of an ivory pointer. Air pressure on the free surface of the mercury in the cistern supports the column of mercury, the length of which is read by a vernier operated by a rack and pinion over a graduated scale marked on the casing. A mercury thermometer attached to the casing gives the temperature of the barometer, and allows corrections to be made.
The Fortin Barometer was commonly used at meteorological stations to measure atmospheric pressure. The advantages of this type of barometer are its portability (inverted), and that it permits the inspection of both free surfaces of mercury whose difference in level have to be measured. The major disadvantage is the cistern and the mercury it contains require frequent cleaning to maintain the instrument's accuracy. This particular Fortin Barometer was in use in the second year laboratory until 1994. Restored recently, it would still be operational, however it contains no mercury.
055 5061A CESIUM BEAM FREQUENCY STANDARD (c1970)
Hewlett Packard. Ser. No. 92400331
Rectangular grey metal casing, front panel consisting of analog time display and three output frequencies, with a pop-down insert panel containing advanced display and adjustment controls.
It uses a beam of state-selected Cs133 atoms subject to microwave induced transitions in their hyperfine energy levels. Atoms prey to transitions are detected by an electron multiplier, the current in which contains a frequency component used to correct the frequency of a quartz oscillator. Provides standards of 5MHz, 1MHz and 100khz.
Similar frequency standards were flown around the world in commercial airlines to prove experimentally relativity theory. Relativity (special) predicts that clocks that stay at home will read a longer time than ones which travel, although in the context of flying around in a plane, the time difference is of the order of 40 to 275 nanoseconds. The Cesium clock keeps time with accuracy of one part in 10^11 and thus is adequate for such experiments. This particular clock was used in experiments with ULF waves for the Omega Global Navigation System (a Navigation system for submarines using ULF waves to triangulate position). ULF waves are affected by the ionosphere, and such a frequency standard is needed to determine its effects.
056 RUBIDIUM FREQUENCY STANDARD MODEL 304-B (c1970)
General Technology Corporation, USA
Instrument provides standard frequency outputs of 5 MHz, 1 MHz and 100 kHz, via BNC terminals mounted on the front panel.
A vapour of Rubidium contained within a small glass cell has an unvarying absorption frequency fo of approximately 6834.68 MHz. The crystal oscillator within the device nominally operates at a frequency f, an integral submultiple of fo. An error signal proportional to the difference (f-fo) is developed and applied to the oscillator, such that the difference is reduced toward zero. In this way, the stability of the Rubidium frequency is transferred to the oscillator, whose signal is translated into the standard output frequencies. The device provides a quoted long term stability of 1 part in 1010.
This particular instrument was used by the late Dr. J. Crouchley, formerly of the department's ionospheric group, in VLF monitoring experiments.
Reference: Operating Instructions. Model 304-B. Rubidium Frequency Standard. General Technology Corporation, Torrance, California (undated).
123 ELECTRICALLY DRIVEN TUNING FORK
Mounted on a base of timber, with a glass fronted wooden cover, is a steel assembly holding the tuning fork and two movable electromagnets, one between the two prongs at the end of the fork, and the other closer to the fork base with coils on either side of the lower prong.
This device was used to maintain the vibration of the tuning fork for long periods of time, in experiments where a constant and well defined pitch was required, e.g. Doppler effect. Essentially, the apparatus functions by attaching a battery across one of the fork prongs. The current thus produced, causes the electromagnet to do work on the prong when it is moving away. The circuit is broken when the prong is moving back towards the magnet so that this advantage is not lost. This interrupted current is usually achieved by using a rigid wire contact between the prong and one terminal of the voltage source.
References: Poynting & Thomson, SOUND, Charles Griffin & Co., London, 1900, pg.42.
339 METTLER H10Tw ANALYTICAL BALANCE
Mettler, Zurich (c 1970)
The unit is housed in a die cast metal case, with sliding side windows providing access to the measuring pan suspended from above. Above and behind this chamber is housed the balance mechanism. The digital readout and dials used to operate the apparatus are attached to the front console.
It is estimated that weights and balances have existed for the purposes of barter and exchange from at least 3000 BC. Based on these most ancient concepts of balance, this unit employs some twentieth century innovation in creating a convenient and accurate weight measuring device. The H10Tw was produced for laboratory applications by the Swiss balance manufacturer Mettler. This style of mechanical balance was regarded as the standard device for laboratory measurements during the 1970s and 80s.
The balance consists of a beam, one end of which supports the pan and adjustable weights and the other which supports the counterpoise weight (equal in mass to the pan plus the adjustable weights). The in-built adjustable concentric ring weights are mechanically arranged using dials on the front console. After placing the object of interest on the pan, equilibrium over a synthetic sapphire knife edge is broadly reached by removing the appropriate ring masses above the pan. The small deviation from equilibrium is then measured on an engraved optical scale placed in a reticle appended to the end of the lever. Light incident on the scale travels through a series of lenses and mirrors to be projected onto the rear of the front console. Ultimately, the balance measures to a precision of 0.05 mg over a range from zero to 160 grams. The H10Tw also features symmetrical air damping, an in-built taring facility and zero point and sensitivity adjustments.
Purchased for A$435 around 1970, the balance found routine laboratory application in The University of Queensland Pathology Department, being donated to the Physics Museum in 1996.
1. T. Buckley (1985) Instrument Maintenance and Operation for Laboratory Assistants. Canberra: International Development Program of Australian Universities and Colleges Ltd.
2. J.T. Stock (1969) Development of the Chemical Balance, HMSO.
342 CAHN RH ELECTROBALANCE (C.1965)
Cahn Division, Ventrol Instruments Corporation / No. 24789 / Patents / US 3,224,517 / UK 978,214 / RE 26100
Metal stand supporting cylindrical glass housing containing thin metal tubing and an electrical device. Two pans can be suspended, with glass sample chambers clamped around them (one of each missing). Metal controller box, 33*18*25, with several dials. Three filters inside, probably to filter out electrical frequencies. Capacity: 0.2 mg to 20 g. Zeroing capability. With mass on pan, tube deflected and compensating torque was applied by passing current through meter coil to straighten tube. Measured current was then proportional to weight or force. Usually attached to chart recorder. Used in University of Queensland Chemistry laboratories to measure force due to diamagnetism of chemicals in magnetic fields.
344 STANDARD YARD
RABONE & SONS MAKERS BIRMm
Brass, marked at one inch intervals, and at 1 ft and 2 ft. First inch divided into eighths. Stamped shield with lion and NSW at one end, another larger one at other end together with GR/V/SM/16. ER/II/IS between 20 and 21 inches. On reverse, 111 stamped, dymo label J107. Lacquer worn through in many places.
Until the 1960s police stations in western New South Wales were issued with standard yards to resolve disputes.
The yard (yd) is the basic unit of length in the imperial system of weights and measures. In Australia, the imperial system was the standard system of measurement until the Metric Conversion Act was passed in 1970. This set in motion the process of converting all measurements in the country into the metric or SI system. This system of measurement uses the meter as its basic unit of measurement and a yard is 0.9144 meters.
The primary advantage of the metric system over the imperial system is the use of powers of ten to relate units of the same dimension (e.g. length, time, mass) such as the millimeter, centimeter and kilometer. This is not the case in the imperial system in which a yard can be expressed as three feet or thirty-six inches. Other units defined in terms of the yard include the pole (5.5 yd), the chain (22 yd), a bolt of cloth (40 yd), the furlong (220 yd) and the mile (1760 yd). These units were derived for commercial or industrial use and were standardised in Australia by the National Standards Laboratory which became operational in 1939.
Until recently, the imperial system was the national standard in Great Britain. The basic unit of length was the imperial standard yard and this was defined as the distance between two lines on a bronze bar made in 1845. (This is similar to the standard yard on display.) This bar made in 1845 replaced an earlier standard yard which had been destroyed by fire in 1839.
In the United States of America, the imperial system was used until 1889 when the nation officially converted to the metric system. One reason that has been given for this change was that the imperial standard yard has been shrinking at a rate of 1.5 millionths of an inch per year. However, unlike in Australia, no program to enforce conversion was instituted, with the result that the USA is now one of the few countries still using the old system.
1. J. Paxton, The New Illustrated EVERYMAN'S ENCYCLOPEDIA, Octopus Books Limited, London, 1984, vol 4 pg1066-1067 "Metrology"
2. Australia, New Zealand ENCYCLOPEDIA including Papua New Guinea, Bay Books Pty. Ltd., Sydney, July 1975, vol 12 pg990-991 "METRIC CONVERSION" vol. 13 pg1058 "NATIONAL MEASUREMENT LABORATORY"
3. Microsoft Encarta 96 Encyclopedia, Microsoft Corporation, United States, 1996, "Weights and Measures".
352 Mercury Sphygmomanometer (c1940)
THE ARMOURED / ELLISCO / SPHYGMOMANOMETER / MADE BY / ELLIOTS 8.../ CENTER...
Air Flow Control Dial : W. A. Baum Co. Inc / Copiague NY / Air-Flo Control
Rubber Bulb : BAUMOMANOMETER
1940's Mercury Sphygmomanometer in black lacquered case. A black rubber bulb is attached via approx 50cm black rubber tubing to a 12.5cm inflatable cuff, which is attached by approx 80cm tubing to a chrome-plated U-tube manometer with a scale from 0 - 300mm Hg.
The bulb contains two one-way valves. The valve at the free end allows air to enter. When the bulb is squeezed, this valve closes and air is propelled through the second one-way valve to the cuff. When the pressure in the cuff increases, mercury moves from the reservoir into the scaled column up to the appropriate level. Between the bulb and the cuff is a third valve which allows the cuff to be deflated. Mercury sphygmomanometers similar to this are still in use today.
To measure blood pressure:
The cuff is wrapped around a superficial artery (usually the brachial) and inflated using the rubber bulb. The high pressure in the cuff is transmitted to the artery, which eventually collapses, inhibiting blood flow to the lower arm. The air in the cuff is slowly released, lowering the pressure. When the pressure falls to just below systolic pressure, the artery opens slightly, allowing blood to flow for a short time until the arterial pressure falls below the cuff pressure and the artery is occluded again. The high velocity, turbulent flow produces vibrations that can be detected by a stethoscope, and the pressure on the manometer at the point when the sounds are first heard is determined to be the systolic blood pressure. As the pressure is lowered further, the opening time of the artery becomes longer with each cardiac cycle until the flow becomes laminar and the sound stops. The pressure on the manometer at this point is identified as the diastolic pressure. The pulse pressure is taken as the difference between the systolic and diastolic pressures, while the blood pressure is expressed as systolic pressure over diastolic pressure.
L. Geddes, The Direct and Indirect Measurement of Blood Pressure, Year Book Medical Publishers, Chicago, 1970, p88-89
L. Sherwood, Human Physiology : From Cells to Systems, Wadsworth Publishing, London, 1997. p312-313
M. Yeats, Maintenance of a Mercury Sphygmomanometer, Equipment, Issue 2, Article 7, 1992
23.5 * 2.5
The stroboscope is essentially a more complicated variation of the tuning fork. At the top of the instrument, there are two steel plates (or diaphrams); each with a slit at the centre and overlapping, which are clamped at the end of the two prongs, by means of screws. The stroboscope is 23.5cm in length, 2.5 in width and comprised of steel.
When the two prongs are at rest, the overlapping slits are perfectly aligned so that light may pass through both. If the fork is then caused to vibrate, it is possible to see through the slits twice in each complete period, that is, 2n times per second, where n is the frequency. Hence the stroboscope is used in many instances to accurately determine frequency as an object vibrating or rotating at the same frequency will appear stationary when viewed through the slits.
E.G.Richardson, Sound A Physical Text Book, Edward Arnold Publishers LTD, London,
Alexander Wood, The students Physics Volume II: Acoustics, Blackie and Son LTD, London, 1940, p318.
B.L.Worsnop and H.T.Flint, Advanced Practical Physics for Students, Methuen and Co. LTD, London, 1957, p 335.
365 PORTABLE AIRFLOW TESTING KIT (MARK 5)
Airflow Developments Ltd, England. No. 4586
Portable airflow kit, includes manometer (small air flow anemometer), pitot tube, thermometer, adjustable metal ruler scale for varying inclinations of pressure tube,, adjustable leveling screws, g-clamp hole in back of case though g-clamp is missing, paraffin refill bottle (empty), pouring funnel for paraffin, appropriate tubing and operation manual all kept in small portable polished wood case.
This airflow kit was designed to measure flows of small size. It was designed for use in the field (this one was probably used in the vet school to monitor ventilation for farm animals), given that it has four inclinations for different scales, g-clamp support and two inbuilt sprit levels. The manometer has four operating modes: positive air pressure, negative and differential with both pitot tube and orifice plate (orifice plate not included). The manometer used dyed paraffin with a specific gravity 0.787 at 60ºF as the working liquid.
The manometer must be made level in horizontal mode before use. This can be done with two adjustable knobs under the manometer limb. The pressure level can be calibrated by adjusting the knob on the front panel. The gauge measures in 'inches water gauge'.
Small floating dial in wooden case on loan to museum. Southern hemisphere dial apparently marked out for the lattitude of Melbourne,
and exhibiting about 8 degrees of magnetic deviation, also appropriate for that location.
Small floating dial in a brass case. Incomplete.
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