“Funny! Such a device as must have been used would need power and lots of it for operation. Well, I’ll try my luck. Carnes, help me unpack and set up the rest of my apparatus.”
With the aid of the operative, Dr. Bird unpacked two of the burros and extracted from cases where they were carefully packed and padded some elaborate electrical and optical apparatus. The first was a short telescope of large diameter which he mounted on a base in such a manner that it could be elevated or depressed and rotated in any direction. At the focal point of the telescope was fastened a small knot of wire from which one lead ran to the main piece of apparatus, which he sat on a flat rock. The other lead from the wire knot ran into a sealed container surrounded by a water bath under which a spirit lamp burned. From the container another lead led to the main apparatus. This main piece consisted of a series of wire coils mounted on a frame and attached to the two leads. The doctor took from a padded case a tiny magnet suspended on a piece of wire of exceedingly small diameter which he fastened in place inside the coils. Cemented to the magnet was a tiny mirror.
“What is that apparatus?” asked Carnes as the doctor finished his set-up and surveyed it with satisfaction.
“Merely a thermocouple attached to a D’Arsonval galvanometer,” replied the doctor. “This large, squat telescope catches and concentrates on the thermocouple and the galvanometer registers the temperature.”
“You’re out of my depth. What is a thermocouple?”
“A juncture of two wires made of dissimilar metals, in this case of platinum and of platinum-iridium alloy. There is another similar junction in this case, which is kept at a constant temperature by the water bath. When the temperatures of the two junctions are the same, the system is in equilibrium. When they are at different temperatures, an electrical potential is set up, which causes a current to flow from one to the other through the galvanometer. The galvanometer consists of a magnet set up inside coils through which the current I spoke of flows. This current causes the magnet to rotate and by watching the mirror, the rotation can be detected and measured.
“This device is one of the most sensitive ever made, and is used to measure the radiation from distant stars. Currents as small as .000000000000000000000000001 ampere have been detected and measured. This particular instrument is not that sensitive to begin with, and has its sensitivity further reduced by having a high resistance in one of the leads.”
“What are you going to use it for?”
“I am going to try to locate somewhere in these hills a patch of local cold. It may not work, but I have hopes. If you will manipulate the telescope so as to search the hills around here, I will watch the galvanometer.”