THERMOMETRY. 



427 



In Air. 



Temperature of the Temperature of Frog's 

 Air. Stomach. 



40-4 C. 



35-8 



27'4 



19-8 



16-4 



14-7 



6-2 



5-9 



31 -7 C. 



24-2 



19-7 



15-6 



14-6 



10-2 



7'6 



8-6 



Temperature of different Animals. Birds Gull, 37-8; swallow, 44-03. 



Mammals Dolphin, 35*5; mouse, 41*1. Reptiles Snakes, 10-12, but higher 

 when incubating. Amphibians and fishes 0'5-3 above the temperature of the 

 surroundings. Arthropoda 0'l-5'8 above the surroundings. Bees in a hive, 

 30-32, and when swarming, 40. The following animals have a temperature higher 

 than the surrounding temperature: Cephalopods, 0'57 ; molluscs, 0'46; echino- 

 derms, 0'40 ; medusae, 0'27 ; polyps, 0'21C. 



208. Methods of Estimating Temperature 

 Thermometry. 



Thermometry. By using thermometric apparatus, we are enabled to obtain 

 information regarding the degree of heat of the body to be investigated. For this 

 purpose, the following methods are employed : 



A. The Thermometer (Galileo, 1603). Sanctorius made the first ther- 

 mometric observations on man (1626). Celsius (1701-1744) divided his ther- 

 mometer into 100 parts, and each part was again divided into 10 parts, so 

 that T VC. could be easily read off. All thermometers which have been used for 

 a long time give too high readings (Bellani), hence they should be compared, from 

 time to time, with a normal thermometer. When taking the temperature, the 

 bulbs ought to be surrounded for 15 minutes, and during the last 5 minutes the 

 mercury column ought not to vary. A very sensitive thermometer will indicate 

 the temperature after 7 seconds if the urine-stream be directed upon its bulb 

 (Oertmann). Minimal and maximal thermometers are often of use to the 

 physician. 



Walferdin's metastatic thermometer (Fig. 167) is specially useful for comparative 

 observation. The tube is very narrow in comparison with the bulb, and in order 

 that the stem be not too long, it is constructed so that the amount of mercury can 

 be varied. A quantity of mercury is taken, so that with the temperature expected 

 the thread of mercury will stand about the middle of the stem. A small bulb at 

 the upper part of the stem receives the excess of Hg. Suppose a temperature 

 between 37-40C. is to be measured, the bulb is first heated a little over 40C., it 

 is then suddenly cooled, and shaken at the same time, so that the thread of mercury 

 is thereby suddenly broken above 40. The tube is so narrow that 1C. is equal to 

 about 10 centimetres of the length of the tube, so that rfaC. is still 1 millimetre 

 in length. The scale is divided empirically, but the value of the divisions must be 

 compared with a normal thermometer. 



KronecTcer and Meyer used very small maximal "outflow thermometers '*' (Dulong 

 and Petit), and caused them to pass through the intestinal canal, or through large Fig. 167. 

 blood-vessels. The mercury flows out of the short open tube, and of course more Walferdin's 

 flows out the higher the temperature. After these small bulbs have passed Metastatic 

 through the animal, a comparison is instituted with a normal thermometer to Thermo- 

 determine at what temperature the mercury reaches the free margin of the tube. meter. 



