The Life of the Grasshopper 



servation of heat. The Mantis anticipated 

 us in a knowledge of non-conducting bodies. 



We owe to Rumford, 1 the natural phi- 

 losopher, the following curious experiment, 

 which fittingly demonstrates the low con- 

 ductivity of the air. The illustrious scientist 

 dropped a frozen cheese into a mass of foam 

 supplied by well-beaten eggs. The whole 

 was subjected to the heat of an oven. The 

 result in a short time was an omelette 

 sou/flee hot enough to burn the tongue, with 

 the cheese in the middle as cold as at the 

 beginning. The air contained in the bubbles 

 of the surrounding froth explains the strange 

 phenomenon. As an exceedingly poor thermal 

 conductor, it had arrested the heat of 

 the oven and prevented it from reaching the 

 frozen substance in the centre. 



Now what does the Mantis do? Pre- 

 cisely the same as Rumford: she whips her 

 white of egg into an omelette sou/flee, to 

 protect the eggs collected into a central 

 kernel. Her aim, it is true, is reversed : her 

 coagulated foam is intended to ward off the 

 cold, not the heat. But a protection against 



1 Benjamin Thompson (1753-1814), an American loyal- 

 ist, created Count Rumford in Bavaria, where he became 

 minister for war. He discovered the convertibility of 

 mechanical energy into heat. Translator's Note. 

 160 



