150 Domestic Science 



the scale is marked, from returning to the bulb imme- 

 diately the thermometer is removed from the mouth 

 or armpit of the patient. The doctor or nurse is thus 

 able to discover the body temperature of the patient 

 after the removal of the clinical thermometer. , To 

 prepare the instrument for further use, it is held by 

 the end further from the bulb and gently swung with a 

 circular motion at arm's length. The thread of mercury 

 is thus caused to pass the constriction into the bulb. 



Exercise for Student. 



Determine suitable ranges of scale for clinical thermometers in 

 which the Centigrade and Reaumur scales of temperature are used. 



The observation of the lowest or highest tempera- 

 tures recorded in a given position during a known 

 interval is often of service. For use in this connection, 

 specially fitted thermo- 

 meters are used. Fig. 48 _ *L_ * 

 shows a portion of the *" 

 stem of a thermometer K 48 



designed to register mini- 

 mum temperatures. The liquid made use of is alcohol 

 and a small steel index, shaped like a dumb-bell, is im- 

 mersed in the alcohol. The thermometer tube is placed 

 in a horizontal position. The extremity of the alcohol 

 column, in moving towards the bulb as the temperature 

 falls, carries with it the index, since the resistance offered 

 by the latter is insufficient, to cause it to break through 

 the surface of the liquid. On the other hand, a rise in 

 temperature does not affect the position of the index, 

 the alcohol passing freely without moving it. Thus the 

 end of the index further from the bulb of the instrument 

 shows the lowest point reached by the liquid, and hence 

 the minimum temperature which has been experienced 



