(104) 
hold each 25 or go pounds^ and thefe theycxpofe to clear 
Nights h and if there be any impurity remaining, it will fall 
to the bottom : Afterwards ttey break the Pots, and dry 
the Salt in the Sun. One might m^ke vaft quantities of Salt- 
petre in thefe parts h but the Country People feeing that IVe 
buy of itj and that the EngUJIo begin to do the fame^ they 
now fell us a Maon of 6 pounds for two Ru^ias and a half^ 
which we had formerly for half that price. 
An Account ef Hevelius his Prodromus ComettcQs, 
together rvith fome Animadverftons made upon 
it by a French Philofopher. 
This excellent Dantifcan Aftronomer^ Heveliuf^ in his Vro^ 
dromns (by him fo caird, becaufe it is as a Harbinger to his 
Cometegraphy^ which hath already fo far paffed the Prefs, 
that of twelve Books there are but three remaining to be 
Printed) gives an Account of the Obfervations he hath 
made of the F#>y? of the two late Gomcts 5 referving thofc 
he hath made of xhtfecond^ for that great Treatife, where 
he alfo intends to deliver the Matter of this frft more parti- 
cularly and more folly then he hath done here. 
In this Account he reprcfents the Rife^ Place, Courfe, 
Swiftnefsa Faces and Train of this Comet 5 interweaving 
his Conceptions both about the Region of Comets in gene- 
ral fwhether it be the -^/r, or the JS/^er and theGaufes 
of their Generation : In the fearchof which latter, he in- 
timates to have received much afEftance from his Telefcope. 
He obferved this Comet not before Decemb. (though he 
conceives it might have been fcenflncc Govern. i^.fiM) & he 
faw it no longer then Tdr. /, ; though feveral others have 
feen it both fooner, and later : and though himfelf continue 
cd to look out for it till March y.fi. n. but fruitlefly, where- 
of he thinks ttaiereafon to bave been Us too great diftance 
and tenuity. 
He 
