Royal Society. 107 
as a reafonablc medium, prefume that they arc generally about 
the magnitude of our fun 5 let us then, for inftance, fuppofc the 
dog-liar to be lb • the diftance from us to the fun being about 100 
times the fun's diameter, it is evident, that the angle under 
which the dog-ftar is leen in M. Hiiygen's telelcope irjufi: be 
nearly the fame with the angle of its parallax to the fun's dif- 
tance, or femidiameter of the earth's annual orbit 5 ib that the 
parallax to the whole diameter can be but double fuch a quantity, 
as even to M. Huygens's nice oblervation is altogether inlenfible^ 
the diftance therefore of rhe fixt ftars leems hardly within the 
reach of any of our methods to determine; but from what has 
been laid down, we may draw fbme conclufions, that will much 
illuftrate the prodigious vaftnefs thereof, i. That the diameter 
of the earth's annual orbit, which contains at lea ft 160 millions 
of miles, is but a point in compariibn cf this diftance, at leafl it 
muft be above 6000 times the diftance of the fun 3 for if a flar 
ihould appear thro* the ar'brefaid telefcope half a minute broad, 
which is a pretty fenfible magnitude, the true apparent diameter 
would not exceed 18"', which is lefs than the 6'oooth part of the 
apparent diameter of the fun ^ and confequently, the fun's diftance 
is not the doooth part of the diftance of the ftar. 2. That could 
we advance towards the ftars 99 parts of the whole diftance, and 
have only the looth part remaining, the ftars would appear lit- 
tle bigger to us than they do here 5 for they would ihew no 
otherwife than they do thro' a telefcope, which magnifies an hun- 
dred-fold. 5. That at leaft 9 parts in 10 of the fpace between 
us and the fixt ftars can receive no greater light from the fun, or 
any of the ftars, than what we have from the ftars in a clear night. 
4. That light takes up more time in pafling from the ftars to us, 
than we in making a Wefi India voyage, which is ordinarily 
perfbrmed in fix weeks 3 that fbund would not reach us at that 
iiiftance in 50000 years; nor a cannon-bullet in a much longer 
time; this is eafily computed, by allowing, according to Mr. New- 
toriy 10 minutes for the pafTage of light from the fun hither, 
and that Ibund moves above 1 500 feet in a iecond of time. 
Obfervations on epidemical Diftempers ; by iDr. Tho. Molyneux. 
Phil. Tranf N° 209. p. 105. 
AB O U T the beginning of November 1^95, after a conftant 
courie of moderately warm weather for the fealbn, upon 
the fall of Ibme fnow, of a fudden it grew extremely cold, and 
loon after there fucceeded ^JomQ few days of a very hard froft ; 
upon which rheums of all kinds, fuch as violent coughs, that 
O 2 chiefly 
