{ii ] 
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- 
fiderable improvements we owe in — 
this regard to Abbé Fontana, will 
appear in the introduction Le! the 
| fecond part of this Work. 
ADVER- 
