ratus was disordered by the experiment, 

 and on other accounts, he did not pursue 

 it so far as he had intended, it was not 

 wholly without success ; and the con- 

 clusions that may be drawn from it are 

 curious and important 1 ." 



After describing the apparatus which 

 had been employed, Priestley proceeds 

 to show that the conclusions which its 

 contriver was disposed to draw from his 

 observations, as far as they had gone, 

 pointed to the " mutual penetrability of 

 matter." He states that the ingenious 

 hypothesis of Boscovich on this subject, 

 " or at least one that is the same in every- 

 thing essential, occurred also to my friend 

 Mr Michell, in a very early period of 

 his life, without his having had any 

 communication with M. Boscovich, or 

 even knowing that there was such a 

 person. These two philosophers had 

 even hit upon the same instances, to 

 confirm and illustrate their hypotheses, 



1 Op. clt. p. 387. 

 80 



