£ *°5 3 
XI. An Improvement propofed in the crofs 
* Wires of Lelefcopes^ by Dr, Wilfon, of 
Glafgow. In a Letter to the AJlrono - 
mer Royal. 
College, Glafgow, Oft. 25, 17 73 * 
S I R, 
Redde,Dec. 23, ir Have lately put in practice a method 
Xj15 ' A improving the crofs wires, that are 
made ufe of in agronomical telefcopes, which has 
pleafed me fo much, that Ppropofe, in this letter, to 
give you an account of it, knowing that you are 
always warmly interefied in the fuccefs of any thing 
of this nature. 
It has been hitherto a defideratum to draw fil- 
ver wire fine enough for aftronomical ufes. I 
need not mention the inconveniences, attending 
our being limited in this particular, as they will, 
of their own accord, occur to you. I therefore 
proceed to defcribe the means, 1 have fallen upon, 
of obviating the difficulty. This, in practice, is 
extremely fimple, and confifts in nothing but in 
flattening^ the fined: wires, which are now drawn. 
I have made the experiment, upon filver wire, 
which is marked 500 to the inch. Having pre- 
Vol. LXIV. P pared 
