Thermopile #10212
A thermopile is a set of thermocouples connected in series. When connected to a sensitive galvanometer and properly aimed it is able to detect the heat from a match across the room. In a prism spectrum it can be used to detect the infrared radiation beyond the visible part of the spectrum.
Reference: Sutton, Demonstration Experiments in Physics, New York, 1938, p.416.


Actinometer #10096
Ducretet á Paris
The actinometer is one form of pyrheliometer, a device to measure the intensity of sunlight. It was invented in 1825 by John Herschel but the form of the present instrument is due to Violle. It consists of two concentric hollow spheres. The space between them is filled with water and a thermometer with a blackened bulb is inserted to the center of the inner sphere. The device is oriented so that sunlight passes through one aperture and through to the thermometer bulb. From measurements of the rate of rise of the temperature of the bulb and rate of fall when the shutter is closed, one can calculate the solar constant and even obtain a value for the temperature of the sun.
References: Max Kohl Catalogue No. 100 (c.1927) p.769, Robert Bud and Deborah Jean Warner, Instruments of Science: An Historical Encyclopedia, New York, 1998, pp.15-17.


Piezometer #10182
The piezometer is a device to measure pressure and the compressibility of liquids. This is a form devised by Regnault and was used to show that water is nearly incompressible.
Reference: Max Kohl Catalogue No. 100 (c.1927) p.312.

Vacuum Pump and Bell Jar

Vacuum Pump and Bell Jar #10077 and 10079
Richards and Co., New York
The bell jar is evacuated by repeated operation of the plunger. A bell placed inside the jar cannot be heard when sufficient air has been removed, showing that a medium is necessary to conduct sound.
Reference: Eimer and Amend BCM Catalog (1927) p.652.

Magdeburg Hemispheres

Magdeburg Hemispheres #10078
E.S. Ritchie, Boston
This apparatus used to show the pressure of the atmosphere. When the two hemispheres are placed together and the interior evacuated, it takes an unexpectedly large force to pull them apart. This was first demonstrated by Otto von Guericke (1602-1686) who was the Mayor of Magdeburg, Germany. He invented the vacuum pump and gave a spectacular public demonstration in 1654 using larger hemispheres and two teams of horses.
References: I. Bernard Cohen, Album of Science, New York, 1950, p.122; J.D. Bernal, Science in History, Vol. 2, Cambridge, MA, 1969, pp.470-72; David Wheatland, The Apparatus of Science at Harvard, 1765-1800, Cambridge, 1968, pp.112-13.

Pascal’s Vases

Pascal’s Vases #10478
Water is added to the level indicated by a horizontal rod and an indicator shows the pressure at the bottom. Three differently shaped "vases" can be used to show that the pressure depends only on the depth, not on the shape of the vessel or the amount of water contained in it.
Reference: Max Kohl Catalogue No. 100 (c.1927) p.300.

Hydraulic Ram

Hydraulic Ram #????
This model demonstrates how the inertia of a falling body of water can be used to raise a small portion of that water to a point higher than its source.
References: Max Kohl Price List No. 100 (c.1927), p.308; Central Scientific Co. Catalog J-141 (1941), p.1119.

Specific Heat Capacity Demonstration
Drawing of Specific Heat Capacity Demonstration Instrument illustrating back and front

Specific Heat Capacity Demonstration #10378
E. Leybold's Nachfolger
There are four vertical rods with cylindrical samples of different materials labeled "Lead," "Tin," "Iron" and "Brass." These rest in a shallow tray but can be raised and held in place by a locking mechanism. They are heated to the same temperature by hot water in the tray, then raised to allow insertion of a block of paraffin on to which they are lowered. The distances they penetrate as they melt the paraffin depend on their particular specific heat capacities.
Reference: Max Kohl Price List No. 100 (c.1927), p.773.
Also, thanks to Paolo Brenni for information on the operation of this device.

Model of a Ventilator

Model of a Ventilator
The pill-box shaped enclosure contains a separate assembly consisting of a disk with vanes with can be rotated to act like a fan. When the outer enclosure is removed the effect of the moving air on a nearby flame is minor. But when the enclosure is placed over the rotating vanes the air is directed through the tangential outlet so the flame is strongly deflected. Thanks to John A. Daffron who spotted the device in a Leybold catalogue.
Reference: E. Leybold Nachfolger catalogue 1900-1910.