of Heat in the Prismatic Spectrum. S^aS 



U III 



Deeper in the green SO 



Ditto without screen 3 8 



In the yellow — ditto 4; 9 



In the red 5 11 



Close under the red (yet a reddish glimmer felH ^ - 



on the upper part of the bulb) .... J 



Half an inch below the red . 4 



I must observe, that the measurements here given are all 



from the highest point of the bulb to the limit of the colour. 



If the distance of the centre of the bulb be required, l-ith of 



an inch must be added to the given distance. 



Thus in this prism the greatest heat showed itself in the 



red ; and the difference between that and the violet was 4" 8'". 

 Exp. 2. — With the same prism, No. 1, on another day. 



Distance of the thermometer six feet. 



Height of the thermometer by the side of the coloured 



spectrum at the elevation of ^^ m 



Half an inch above the violet 5 Of 



Half ditto above the prismatic violet itself ..52^ 



Quarter ditto 5 3| 



Close above the violet 5 5 



Half in ditto 5 8 



In full violet 6 5^ 



Half in the blue 6 9i 



In blue 7 5 



Half in greenish yellow 8 3 



In the yellow 9 1^ 



Half in the red 9 9 



Entirely in the red 107 



Half in the red, half below it 10 3 



Close under the red 101 



also to 10 3 



Quarter of an inch below the red 9 3 



Half ditto ditto 8 



One ditto ditto 7 



and 6 9 



Two ditto ditto 6 1 



At an equal height without the spectrum ... 5 6 



In this experiment then, an increase of temperature was 

 shown even half an inch above the violet; and the difference be- 

 tween the heat in the shade and that in the Ijght, half an inch 

 above the violet, amounted to If lines. 'Fhe difference be- 

 tween half an inch above the violet and the maximum of heat, 

 which again fell in the full red, 5 in. 4i lines. But it must be 



noticed 



