University of Texas Demonstration Room, ca. 1900
A description of some of the apparatus shown appeared in an American Journal of Physics (Am. J. Phys, 76, 1011 (2008)) contribution by Thomas B. Greenslade, Jr., of Kenyon College. In referring to a copy of this photo supplied him by David Gavenda, he writes, “ In the lower left-hand corner can be seen a Wimshurst static electricity generator, an electric egg (for discharges in rarefied vapors), a set of four Leiden jars and Bohnenberger’s electroscope. On the bottom shelf of the next bay is a thermoelectric generator [Am. J. Phys. 72, 1516 (2004)], and in the third bay can be seen the circular scale of a magnetic dip needle that is still in the collection. Other pieces of apparatus still in regular use at Texas are the two wave machines in the lower half of the end cabinet. “ According to Professor Arthur Lochenvitz, Colonel Breckenridge went to Philadelphia with Professor Mather and got a good portion of the Centennial of 1876 Exhibit that was physics related. Mather joined the faculty in 1898 and Breckenridge was a regent from 1886-1911. Most of the engineering and physics equipment had been moved to the new Smithsonian Arts and Industry Building in 1881. Maybe they got the leftovers in Philadelphia. The equipment was used for lecture demonstrations. Some of these items are likely in the picture above. Thomas GreenSlade took pictures of many pieces of the UT demonstration equipment. David Gavenda kindly made them available.
Equipment Album |
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Generator |
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Over 100 years ago, the company’s founders, Dr. Carl Siebert und Albert Kühn, recognized an increasing demand for technically high quality, precision thermometers and glass apparatus. They founded the company Dr. Siebert & Kühn GmbH & Co. KG on November 1, 1901, thus laying the foundation for the success story that is SIKA in the development and production of high quality measurement equipment. SIKA is still entirely family-owned and is run by members of the Siebert family in the 4th generation. According to the company, the thermometer had to be made before WWI as the “Cassel” has been written as “Kassel” since 1920. |
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Over 100 years ago, the company’s founders, Dr. Carl Siebert und Albert Kühn, recognized an increasing demand for technically high quality, precision thermometers and glass apparatus. They founded the company Dr. Siebert & Kühn GmbH & Co. KG on November 1, 1901, thus laying the foundation for the success story that is SIKA in the development and production of high quality measurement equipment. SIKA is still entirely family-owned and is run by members of the Siebert family in the 4th generation. According to the company, the thermometer had to be made before WWI as the “Cassel” has been written as “Kassel” since 1920. |
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This thermometer was made by McKesson & Robbins in the U.S.A.) A Beckmann thermometer's length is usually 40 – 50 cm. The temperature scale typically covers about 5 °C and it is divided into hundredths of a degree. With a magnifier it is possible to estimate temperature changes to 0.001 °C. The peculiarity of Beckmann's thermometer design is a reservoir (R on diagram) at the upper end of the tube, by means of which the quantity of mercury in the bulb can be increased or diminished so that the instrument can be set to measure temperature differences at either high or low temperature values. In contrast, the range of a typical mercury-in-glass thermometer is fixed, being set by the calibration marks etched on the glass or the marks on the printed scale.
The upper end of the tube is gently tapped with the finger, and the mercury suspended in the upper part of the reservoir will be jarred down, thus separating it from the thread at the bend (B). The thermometer will then be set for readings between the required temperatures. Interesting sidelight to this company from Wikipedia: The McKesson & Robbins, Inc. scandal of 1938 was one of the major financial scandals of the 20th century. The company McKesson & Robbins, Inc. (now McKesson Corporation) had been taken over in 1925 by Phillip Musica, who had previously used Adelphia Pharmaceutical Manufacturing Company as a front for bootlegging operations. Musica, a twice-convicted felon, used assumed names to conceal his true identity in taking control of the two companies: Frank D. Costa at Adelphia Pharmaceutical and F. Donald Coster at McKesson & Robbins. Although he was successful in expanding the company’s legitimate business operations, Musica recruited three of his brothers, also working under assumed names, one outside the company and two inside it, to generate bogus sales documentation and to pay commissions to a shell distribution company under their control. Eventually, McKesson & Robbins treasurer Julian Thompson discovered the distribution company was bogus. It was eventually determined that about $20 million of the $87 million in assets on the company’s balance sheet were phony. |
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(Pictures courtesy of Professor Dennis McFadden, UT ) |
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(Picture courtesy of Professor Dennis McFadden, UT ) |
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Helmholtz Resonators, belonged to Professor C. P. Boner Helmholtz described in his 1862 book, “On the Sensations of Tone,” an apparatus able to pick out specific frequencies from a sound. The Helmholtz resonator, as it is now called, consists of a rigid container of a known volume, nearly spherical in shape, with a small neck and hole in one end and a larger hole in the other end to admit the sound. When the resonator's 'nipple' is placed inside one's ear, a specific frequency of the complex sound can be picked out and heard clearly. In Helmholtz’ book we read: When we “apply a resonator to the ear, most of the tones produced in the surrounding air will be considerably damped; but if the proper tone of the resonator is sounded, it brays into the ear most powerfully…. The proper tone of the resonator may even be sometimes heard cropping up in the whistling of the wind, the rattling of carriage wheels, the splashing of water.” THE HELMHOLTZ RESONATOR "The resonators that Helmholtz described performed an incredible feat. When sound would hit the (a) opening, the vibrations would excite the volume of air in the body of the resonator. However, because of its peculiar design, the resonator would only transfer and amplify a single tone to the (b) opening, but only if that tone was present in the sound being made. The volume of the body determined which tone was transferred. "Helmholtz would place the (b) opening in his ear and use it to pick out individual musical tones when many were present. For instance, if a three-noted chord was played, and a resonator was present that was tuned to one of those notes, only that note would be audible to Helmholtz. However, if a resonator were present, tuned for a note that was not being played, nothing would be heard. Even if the note the resonator were tuned for was extremely quiet in comparison to the rest, the resonator would amplify the correct note, allowing Helmholtz to hear even the faintest of sounds. "Helmholtz had many resonators of different sizes and shapes. In fact, any rigid structure containing a volume of air connected to the outside via a small opening (hole, port, or neck) that amplifies a particular frequency can be considered a Helmholtz resonator. A very common object that classifies is a standard beer bottle. When a person blows across the top of an empty bottle, a low oo (as in tool) can be heard. Regardless of how hard or soft the person blows, the same note is created, just louder or softer." "…When the air in the opening of a Helmholtz resonator is disturbed, it bounces like a mass on a spring in simple harmonic motion, creating sound. The frequency of the sound created is equal to that of the air's vibration. This frequency is determined by a simple formula, where f is the frequency, v is the speed of sound in air, A is the surface area of the hole, V is the volume of air in the resonator's body and l is the length of the neck or port …."
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Man Lifter ca. 1900
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Pendulum, Gridiron The gridiron pendulum was a temperature-compensated clock pendulum invented by British clockmaker John Harrison around 1726 and later modified by John Ellicott. It was used in precision clocks. In ordinary clock pendulums, the pendulum rod expands and contracts with changes in temperature. The period of the pendulum's swing depends on its length, so pendulum clocks rate varied with changes in ambient temperature, causing inaccurate timekeeping. The gridiron pendulum consists of alternating parallel rods of two metals with different thermal expansion coefficients, such as steel and brass. The rods are connected by a frame in such a way that their different thermal expansions (or contractions) compensate for each other, so the overall length of the pendulum, and thus its period, stays constant with temperature. The gridiron pendulum was used during the Industrial Revolution period in regulator clocks, precision clocks employed as time standards in factories, laboratories, office buildings, and post offices to schedule work and set other clocks. The gridiron became so associated with quality timekeeping that to this day many clocks have pendulums with decorative fake gridirons, which have no temperature compensating qualities. Scientists in the 1800s found that the gridiron pendulum had disadvantages that made it unsuitable for the highest precision clocks. The friction of the rods sliding in the holes in the frame caused the rods to adjust to temperature changes in a series of tiny jumps, rather than with a smooth motion. This caused the rate of the pendulum, and therefore the clock, to change suddenly with each jump. Later it was found that zinc is not very stable dimensionally; it is subject to creep. Therefore, another type of temperature-compensated pendulum, the mercury pendulum, was used in the highest precision clocks. By 1900, the highest precision astronomical regulators used pendulums of low thermal expansion materials like invar and fused quartz. |
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Roget's Spiral, ca. 1900 Roget's Spiral demonstrates that there is an attractive force between two parallel wires carrying electric current in the same direction. The wire is actually coiled in a helix and not in a spiral, prompting the alternative name of Contracting Helix. A pointed iron bob on the end of the helix dips into a pool of mercury, and the upper end of the helix and the mercury are connected to a source of EMF. The current through the helix causes it to contract, breaking the circuit and removing the force between the turns. The bob then falls into the mercury and the cycle starts once more. REFERENCE: Thomas B. Greenslade, Jr., "Nineteenth Century Textbook Illustrations, LVIII: Roget's Spiral", Phys. Teach. 36, 38 (1998) |
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s'Gravesande's Apparatus
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Tonometer Tonometers are secondary frequency standards, and often consist of a series of circular cylinders suspended by light cords from their two nodal points. The frequency is inversely proportional to the square root of the length, which enables the higher frequency rods to be machined to the right lengths. This set of tonometer bars was made by the Standard Scientific Company of New York |
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The 1928 Welch catalogue describes a similar piece of apparatus as "COUNT RUMFORD'S EXPERIMENT, Tyndall's Friction Cylinder. Cylinder 2 cm in diameter and 10 cm long mounted on a standard rod to fit any rotator chuck and with a wood, calf-lined friction clamp. Alcohol cam be made to boil in a short time so as to blow out the cork from the tube .. $2.00" See video of operation. Tyndall Apparatus |
Tyndall's Apparatus From Fondazione Scienza e Tecnica, via G. Giusti 29, Firenze, YouTube Video. |
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Wave Machine, Transverse This is a beautiful machine that I used to illustrate the difference between phase and group velocity. As the cam shaft is rotated the rods move up and down so that the transverse wave of the blue ball moves to the right or left, depending on the rotation direction. You can measure the phase velocity of the wave, however since there is no connection between the rods, then no energy moves with the wave, hence the group velocity is zero. The energy any ball has came through the cam shaft from the operator and arrived at the speed of shear waves in the metal shaft. An alternative demo would be to remove the cam shaft and attach each rod at the bottom to a spring attached to the floor. Now compress the rods with the proper phase and velocity and a wave will also move horizonatally. Again since there is no connection between the rods there is no energy flow.—Mel Oakes |
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Calibration:
(note by Mel Oakes: This frequency expression given below can be calculated by assuming the neck of the container acts as a mass attached to a spring. The large volume acts like a spring, i. e. when the neck mass moves into the volume V, the pressure increases above atmospheric due to compressed volume. When neck “plug” moves out, the pressure in V drops and outside atmospheric pressure pushes it back. Thus the force on the plug of air has a force opposite to its displacement and proportional to its replacement. An equivalent spring constant can be easily calculated and the frequency determined from that of a spring mass system. To calculate the pressure-volume change you must use the PV relationship for an adiabatic process. If so, the formula below will have a gamma (adiabatic index cp/cv in the numerator under the square root sign. This formula permits a measurement of the adiabatic index gamma for the gas.)
The source of the name can be seen from the advertisement at right. The drawing is from 
As the vacuum pump removes the air from the transparent cylinder, the piston at the bottom of the cylinder will be push up by the atmospheric pressure acting on the exposed bottom of the piston. The weight attached to the chain which is attached to the piston will rise. The piston diameter is about 5 inches. With atmospheric pressure at 14.7 lbs/square inch times the area of the piston (pi time radius squared) the force on weight would be 288 lbs for a perfect vacuum. For a 15 kg (33 lbs) weight, the piston will begin to move when the pressure drops by 1/10th of an atmosphere. With mechanical rotary pumps capable of dropping the pressure to 1 Torr (1/000 of atmosphere) The weight rapidly rises following the pump being turned on.
's Gravesande is remembered for, among other things, his invention of a simple experiment demonstrating thermal expansion, which has been used in physics education since. This is known today as "'s Gravesande's experiment" or "'s Gravesande's ring". The apparatus consists of a small metal ball on a chain or handle, and a metal ring on a stand. The ring is just big enough so that when the ring and ball are at the same temperature, the ball fits through the ring. However, if the ball is heated by dipping it into boiling water or playing the flame of a spirit lamp over it, the metal will expand, and the ball will no longer fit through the ring. When the ball has cooled down, it will fit through the ring again.