2,6 Gee, Daltoris Lectures and Lecture Illustrations. 



New Scale. 





Inch 



es of Water. 



Differences 



o 



12 



= 





i'5 2 3 





22 



= 





2"OIO 



•487 



3 2 



= 





2-652 



•642 



42 



= 





3*5 



•848 



5 2 



= 





4*618 



I*Il8 



62 



= 





6094 



1-476 



72 



= 





8 "04 1 



1-947 



82 



= 





io"6i 



2-569 



92 



= 





14* 



3*390 



The curve shown is convex towards the horizontal 

 line of temperatures. 



No. 62. (27" x 19".) Like the previous diagram but 

 the Fahrenheit scale is used. The departure of the curve 

 from a straight line connecting the freezing and boiling 

 points is much less marked than in No 61. 



No. 63 is like No. 61 but larger (32" x 22"). A straight 

 line connecting the 30° and 90° points shows that at 6o° 

 the amount of water that must be precipitated when the 

 temperature falls from 90 to 6o° is considerable. 



No. 64. A still larger diagram (4i"x34 // ) like the 

 last one but designed for a large lecture room. Straight 

 lines are drawn connecting the 30 to 8o°, the 30 to 50°, 

 and the 6o° to 8o° points. 



Sheet 65 



(27" X 19".) This has been intended by Dalton to ex- 

 plain Proposition III. of the "Mathematical Propositions 

 necessary for illustrating and confirming those concerning 

 the Aurora Borealis" (see "Meteorological Essays," p. 154, 

 1834). It shows a series of cylindrical beams equal and 

 parallel to each other, all in a plane perpendicular to the 

 horizon, and at equal distances from the horizon. These 

 beams Dalton demonstrates will appear to an observer 

 like a series of arches of a special shape. The diagram 

 has not been completed. 



