[ lxi ] 



goodnefs of the common air is found 

 to be in proportion to the diminu- 

 tion of the bulk of the two airs. 

 Mr. Magellan, F. R. S. has publifhed 

 a work upon an ingenious con- 

 trivance of his own of this kind, 

 which is to be fold by Mr. Parker 

 in Fleet-Street, with the proper di* 

 rections how to ufe it What con- 

 iiderable improvements we owe in 

 this regard to Abbe Fontana, will 

 appear in the introduction to the 

 fecond part of this work. 



ADVER- 



