190 



Sir H. Daw on the Relations 



veral coinciding measurements taken upon planes produced 

 by cleavage, which when properly made are usually found to 

 agree, — whilst those taken upon the natural planes generally 

 differ a few minutes. In one instance I found 104° 55', not 

 105°. Hence the accuracy of measurements taken as the 

 bases for calculation is very important. 



Primary. 



Measurements taken by 

 the reflective goniometer. 



Measurements of 

 Dr. Walchner. 



M on M' . 

 P on M or M 



al . 



a2 . 



c or c 



e or e' 



M on a 1 . 



a2 . 



a 



1 on a 1' 



a2 , 



c or 6 



a 2 on a 2' . 

 c or c* 



105° 00' 



90 00 



132 32 130° 18 



114 35 119 29 



139 16 141 4 



110 14 



124 10 



135 5 



113 35 



159 40 



95 15 99 22 



162 22 169 10 



120 56 



130 10 121 



108 30 



98 30 



56" 



47 

 54 



8 

 51 



26 



The two measurements given by Haidinger in his transla- 

 tion of Mohs, vol. iii. p. Ill, agree with those of Dr. Walch- 

 ner. 



XL. The Bakcrian Lecture. On the Rclatio?is of Electrical 

 and Chemical Changes. By Sir Humphry Davy, Bart. 

 Pres. R.S. 



[Concluded from p. 104.] 



VII. On the accumulation of electricity, and the chemical 

 changes it occasioiis in voltaic arrangements. 



IN the view of electro-motion adopted by the illustrious in- 

 ventor of the pile, the metals were considered as the only 



affents 



