118 



ARON. 



This danger is avoided by introducing two thermocouples in opposite 

 directions in such places^ the one neutralizing the other. If care is 

 now taken to keep two such junctions {x and y) at equal temperatures, 

 absolute changes in temperature will not produce current from such 

 junctions. This is shown by the following figures, in which Scheme I 

 shows the usual arrangement and Scheme II that employed by me. 



Scheme 1. 



Scheme 



Fig. 1. 



Ci^^ 



According to this principle I have con- 

 structed an apparatus suitable for taking 

 skin temperatures, and also others for 

 taking temperatures inside of clothing or 

 under the skin or even in the rectum of 

 a monkey. Figure 2 is a diagram of the 

 thermocouple used. 

 Constantan in the form of wire (black in the 

 figure) and iron wire (dotted in the figure) each 

 of 1 millimeter diameter were soldered together. 

 The junction at A was kept at a constant tem- 

 perature which could be read to 0°.l by means 

 of a sensitive normal thermometer T, the mercury 

 bulb of which M was at the same point as A. 

 Both wires were hanunered to a fine leaf of about 

 0.1 millimeter thickness at the "thermometric" 

 junction B and soldered together so that two fine 

 plates resulted, which were carefully cleaned from 

 all superfluous solder by sandpaper. These were 

 placed exactly in the same level. This system of 

 wires, surrounded by silk and insulation tape, was 

 inclosed in its upper two-thirds in a glass tube C 

 fitted in its lower one-third into a wooden box H 

 of the shape of a tobacco pipe. The lower part 

 of the glass tube and the wooden box were filled 

 in with melted paraffine P. The lower end of the 

 paraffine was formed into a block, the leaf-like 

 junction B being carefully cleaned from all paraffine, so that there was left only 

 a minute space between B and the paraffine block P. The glass tube C was 

 now inserted into another, larger tube D by means of two rubber stoppers, E 

 and F, E having three holes, one for D and the other two for two glass tubes 

 Gi and G2, which served to circulate water. The iron wires coming from A were 

 fixed in two pole screws S on the upper end of the glass tube C. The wires, 

 I, led to the galvanometer. Finally, D was covered with a layer of felt and 

 cotton K and inclosed in a cylinder of white carton paper L. 



Water entering at Gi and leaving at G2 kept the temperature of the secondary 

 couple A constant even in the hottest sun. Gi was connected by a rubber tube 

 about 3 to 4 meters in length with a tank containing 50 liters of water. The 

 copper wires, I, with a strong coat of yellow silk insulation were coiled in the 

 usual manner. The measurements were taken on a flat roof, while the galvano- 

 meter, connected by means of a copper key, and the wires, I, were inside the 

 room, protected from the sun. The apparatus was freely movable and served 

 the purpose well. I will not designate the form as ideal, but it must be re- 

 membered that it was entirely built in Manila. 



Pig. 2. 



