HEAT OR CALORIC. 39 



nous. But if a glass prism, D O E, be placed before the hole so 

 that the light may fall upon the prism, perpendicularly to its axis, 

 the rays which had before produced the luminous circle will be re- 

 fracted and dispersed, so as to form the spectrum, r g #, consisting 

 of the following colors arranged in the following order red, orange, 

 yellow green, blue, indigo, violet. 



Dr. Hare. 



(/.) These experiments have been fully confirmed by those of Sir 

 H. C. Englefield. Mur. In his experiments there could be no 

 source of deception, because each kind of rays, first separated by 

 the prism, was made to pass successively through a four inch lens 

 covered by pasteboard, except at one place, where was a slit in the 

 paper the focus was thus formed in the air and the thermometers 

 were there applied. 



In Dr. Herschel's experiment, as the rays were thrown on a table, 

 some fallacy might, possibly, have been suspected, from the reflection 

 of the rays. In Englefield's experiment, the thermometer gave the 

 following results. 



Ray. Time. Quantity. Ratio of the effect. 



Blue in 3' from 55 56 1. 



Green 3 54 58 4. 



Yellow 3 56 62 6. 



Full red 21 < 56 72 7.2 



Confines of red 2| " 58 731 6.6 



In full dark, but near the red in 21 " 61 79 21.6 



The difference in the heating power of the spectrum is so great, as 

 to be perceptible to the naked hand. 



(g.) Berard confirmed HerschePs and Englefield's experiments 

 substantially.* 



*Ann. Phil. II, 163. 



