43° Remarks oft a Micrometer, &c. 
Numbers already placed in two Columns of 
the Table, by y and 49 * 
I would juft obferve, that fome Double 
Microfcopeshave a Drawer between the Glaf- 
fes, and by Means of which they magnify 
differently with the fame Glafs : in thefe Mi- 
crofcopes therefore one Pofttion of the Drawer 
ihould be pitched upon as the moft conve¬ 
nient, and the fame ihould conftantly be ufed 
whenever any Magnitude is to be determined 
by the Micrometer applied to the fame. 
The Lattice abovementioned, whole Wires 
are only diftant a Fiftieth of an Inch, may up¬ 
on fome Occafions be found inconvenient in 
viewing of Objects. But it may very eafily 
be taken out and put in occafionally, or have 
its Place fupplied by another whofe Wires 
may be the 20th or the 10th of an Inch 
afunder 5 and this laft efpecially will give no 
Hindrance to common Obfervations, and will 
befides be very ufeful to fuch as would draw 
with fome Exadlnefs any of the Gbjedts 
they examine with their Microfdope* _ 
I am told that Silver Wire may be had to 
make thefe Lattices of, whofe Diameter is 
rather lefs than the feven hundredth Part of 
an Inch. 
The Mention Mr. Folkes makes of a Lat¬ 
tice whole Divisions are W of an Inch, was 
owing to his having experienced the Utility 
of fuch an one in my Microfcope, made by 
myfelf of human Hairs, and faftened exa&ly 
in 
