C 1180] 
tival of Mr. Hally, with which he was very well pleaf- 
ed,- having long delired, that he might have oppor- 
tunity of converfing with feme, well acquainted with 
l^eleJcopicJ^ that fo he might, not by words on- 
ly, but by experience and pradife, evidence to them 
the convenience and certainty of his Oblervations by 
Tlaifi Sights, That Mr. Hally had now (for about a 
months time) diligently oblerved together with him, 
every fair night; That he was already well iatisfied 
upon his own experience/and would, he hoped, fignify 
lomuch to the 7^(?y^/ Society) that he found, upon try- 
al, things far otherwife than had been fuggefted by 
fome ("as it he could not, with his Inftruments and 
naked SijhH\ diftinguifli to one, two, or three Mi- 
nutes.j But intimates, that himfelf was not lo well fa- 
tisfied with Mr. Hally % Inftrument with Telefcopicks ; 
(having found, upon tryal, the fufpicions true which 
before he had of them;) And is very well plealed, 
that he had not been prevailed with, to exchange his 
Tlatn Sights for fuch. And with it, lie tranfmits to 
the I^yal Society , his late Obfervation of the occulta- 
tion of Jupiter by the Moon. 
The 27'\ (which is the laftjis from Mr. H^lly to th^ 
jiuthor s teftifying his great fatisfadlion with the Au» 
thors entertainment ; With the opportunity of conver- 
fing & oblerving with him; With his Inftruments and ac- 
curate Obfervations, far beyond what he could have 
imagined ; And offers himfelf ready ta teftiTy fagainft 
any who fhould hereafter queflion it) the great accurate- 
nefs thereof (wondring at nothing more, than to find 
them fo accurate J and of their great agreement one 
with another; not varying more than by an inconfi- 
derable part of a minute. 
Now the diftinguijhing of f\ (which is aUually diflin* 
guijhed in thefe Injtruments,) is fh nice a matter as anfwer» 
eth, upon Earthy to the twelfth part of an Englifh mile 
(allowing 
