[ I ° 6 ] 
pared a fmall block of fteel, the face of which 
was made very flat and fmooth, a number of the 
wires were ftretched acrofs it, at confiderable inter- 
vals, by having their ends faftened, by pitch, at 
each fide of the block. This done, I took another 
block of fteel, of the fame fize, the face of which 
had been made likewife flat, and the top of it 
rounded, the better to determine the ftroke of the 
hammer j upon applying this, over the wires lying 
upon the firft block, which was firmly fixed in a 
vice, and giving a fmart ftroke with a hammer of 
about five pound weight, I found all of them flat- 
tened in a very even manner. 
That I might have no difficulty of fitting 
thefe wires, fo flattened, into the telefcope, I pur- 
pofely made the face of the fteel blocks a fmall 
matter narrower, than the width of the brafs 
ring, in our tranfit inftrument, upon which the 
crofs wires are fixed. By this means the wires 
retained their roundnefs at both ends, and fo were 
eafily fixed acrofs the ring, by the fcrew-pins, 
when their fine edges regarded the eye. By means 
alfo of a fimple contrivance, which will readily 
occur in practice, I made the horizontal wire to 
go acrofs the others, fo as juft to touch them. 
This horizontal wire was a round one, of 500 to 
the inch, which I purpofely ufed along with the 
others, that I might form fome judgment of the 
effects of flattened ones, when viewed along with 
it in the field. I accordingly found a very ftriking 
diminution of the vifible fubtenfe of thefe wires, 
when compared with the round one ; and this fo 
confiderable 
