TEMPERATURE-TOPOGRAPHY. 385 



at their points. Becquerel needles (III) also may be employed. These are made 

 of the same metals, which are soldered together in continuity. The needles must 

 be well covered upon their surface with brown varnish in order that the currents 

 resulting from the moistening of different metals with the parenchymatous fluids 

 may not interfere with the thermo-currents obtained. Before the investigations 

 are undertaken the extent of deflection on the scale to which a definite difference 

 in temperature in the needles gives rise, thus about i C., must further be deter- 

 mined. In order to do this a sensitive thermometer is fastened by means of a 

 loop to each of the thermo-needles, which are placed in separate oil-baths of a 

 constant temperature, though differing by i C., as can be seen from the ther- 

 mometers. If the circuit is now closed the deflection on the scale will naturally 

 correspond to i. If, thus adjusted, the instrument exhibited a deflection of 150 

 mm., every displacement of the scale of i mm. would equal T i ff C. If this has 

 been determined, either the two thermo-needles can be introduced into the different 

 tissues or organs of animals at the same time, and in this way information be 

 gained as to the prevailing differences in temperature in these portions of the 

 body; or one of the thermo-needles is placed in a bath of constant temperature 

 approximately that of the body in which at the same time there is a sensitive ther- 

 mometer, while the other needle is introduced into the viscus to be examined. 

 In this event the difference in temperature between the tissue and the constant 

 source of heat is learned. For slight differences in temperature, such as usually 

 exist in the tissues of the body, the thermo-electric energy is always proportionate 

 to the difference in temperature between the two needle-elements. 



It is obvious that instead of one pair of needles a multiplicity may be em- 

 ployed. By this means the delicacy of the apparatus naturally is materially in- 

 creased. Thus, v. Helmholtz was able to increase the delicacy of the apparatus 

 to the detection of differences of ^Vcr C. by the employment of 16 antimony- 

 bismuth elements? Schiffer constructed a thermopile of four pairs of needle- 

 elements in a simple manner (Fig. 135, IV) by soldering together alternately 

 wires of iron and German silver. It is intended that four such elements should be 

 introduced into two substances (A and B) to be examined for differences in tem- 

 perature. 



Thermo palpation is the name given by Benczur and J6nas to the following 

 method of examination : If the finger be moved over an uncovered portion of the 

 trunk it will be found that the skin is warmer over parts containing air, such as 

 lungs and intestines, than over parts, normal or pathological, not containing air. 

 The boundaries are said to agree with those determinable by percussion, but 

 this has been disputed. Naturally this difference can be established also by 

 thermometric examination. 



TEMPERATURE-TOPOGRAPHY. 



Although a powerful influence must be ascribed to the blood, on 

 account of its constant movement, in the equalization of the temperature 

 in the different parts of the body, nevertheless an exact equalization is 

 never attained, but noteworthy differences exist in different parts of the 

 body. 



The temperature of the skin has been found to be as follows : 



In the middle of the sole of the foot 32 .26 C. J. Davy made these measure- 

 In the vicinity of the Achilles tendon ... 33.85 C. ments immediately on 

 In the middle of the anterior aspect of arising without dressing, 



the leg 33-5 C. with the temperature of 



In the middle of the calf 33 .85 C. the room at 21. Only 



In the popliteal space 35 C. the inferior surface of the 



In the middle of the thigh 34-40 C. bulb of a thermometer 



In the inguinal fold 35-8o C. otherwise covered came in 



Over the apex-beat of the heart 34-40 C. contact with the different 



On the face in a man 31 C. portions of the skin. 



At the tip of the nose and on the lobule 



of the ear from 22 to 24 C. 



In the closed axillary cavity, the temperature ranges, according to Wunderlich, 

 from 36.49 to 37.25; according to C. v. Liebermeister it is 36.89 C. 



25 



