(50 
vifible effedsupon the rays of Light ^ without any other 
coefficient caufe : and thenj that there is in the Air or Atmo- 
Jphere , fich a variety in the conftituent parts of it ^ both as 
to their <ie;^^ and r^r;'/;/ 3 and as to their divers mutations 
and pofitions one to another. 
He concludeth with two CeleJlMl Ohfervations ^ v/here- 
ofthe<?/^e imports 5 what multitudes of Stars are difcove- 
rable by the Te/e/?^?/^, and the variety of their magni- 
tudes : intimating with all ^ that the longer the Glafles are^ 
and the bigger apertures they will indure^ the more fit they 
are for thefedifcGveries: the affords a delcription of a 
Vale in the Moon j compared with that of Hemlius and 
ciolo 5 where the Reader will find feveral curious and plea« 
fant Annotations 5 about the Pits of the Moon^ and the 
Hills and Coverings of the fame 5 as alfo about the varia- 
tions in the Moon 3 and its gravitating principle^ together 
with the ufej that may be made of this Inftance of a gravity 
in the Moon. 
As to the Inventions of Art^ defcribed in this Book^ the 
curious Reader will there find thefe following : 
1. A Barofcope^ or an Inftrument to (hew all the Minute- 
Variations in the TreJJnre ©f the Air 2, by which he affirms^ 
thathefinds;, that before and during the time of rainy wea- 
ther^ the Prefliire of the Air is lefs 5 and in dry weather^ 
but efpecially when an Eajierly Wind ("which having paft 
over vaft Trafts of Land 5 is heavy with earthy particles ) 
blowsj it is much morej though thefe changes be varied ac- 
cording to very odd LawSa 
2. kHj/grofcope^ or an Inftrument 3 whereby the Waterf 
Jieams^ volatile in the Air , are difcerned ^ which the Nofc 
it felf is not able to find. Which is by him fully defcribed 
in the Obfervation touching the Beard of a mild Oate^ by the 
means whereof this Inftrument is contrived. 
g. An Inftrument for graduating ihermometers ^ to make 
them Standards of Heat and Cold, 
4. A Nem Engin for Grinding OptickGlaJfes ^ by means of 
which he hoges^ that any Spherical Glafles^ of what length 
foever^; 
