VOL. LXIV.] PHILOSOPHICAL TRANSACTIONS. 507 



When they have undergone 3 operations of this kind, they are fit for making 

 coarse brown paper; after 7 or 8 operations, they are prepared for making paper, 

 of a tolerable whiteness. 



The rags, thus prepared, are mixed with water in a cistern, to proper con- 

 sistence; after which it is taken up by a wire frame, to form it into sheets of 

 paper, &c. just in the manner practised in England. 



XL An Improvement proposed in the Cross Wires of Telescopes. By Dr. 



Wilson, of Glasgow, p. 105. 



It has been hitherto a desideratum to draw silver wire fine enough for astrono- 

 mical uses. The means fallen on by Dr. W. of obviating the difficulty, in practice, 

 is extremely simple, and consists in nothing but in flattening the finest wires, 

 which are now drawn. He made the experiment on silver wire, which is marked 

 500 to the inch. Having prepared a small block of steel, the face of which was 

 made very flat and smooth, a number of the wires were stretched across it, at 

 considerable intervals, by having their ends fastened, by pitch, at each side of the 

 block. This done, he took another block of steel, of the same size, the face 

 of which had been made likewise flat, and the top of it rounded, the better to 

 determine the stroke of the hammer; on applying this, over the wires lying on 

 the first block, which was firmly fixed in a vice, and giving a smart stroke with 

 a hammer of about 5 pounds weight, he found all of them flattened in a very 

 even manner. 



That he might have no difficulty of fitting these wires, so flattened, into the 

 telescope, he purposely made the face of the steel blocks a little narrower than 

 the width of the brass ring, in our transit instrument, on which the cross wires 

 are fixed. By this means the wires retained their roundness at both ends, and 

 so were ea^ly fixed across the ring, by the screw pins, when their fine edges 

 regarded the eye. By means also of a simple contrivance, which will readily 

 occur in practice, he made the horizontal wire to go across the others, so as just 

 to touch them. This horizontal wire was a round one, of 500 to the inch, 

 which he purposely used along with the others, that he might form some judg- 

 ment of the effects of flattened ones, when viewed along with it in the field. 

 He accordingly found a very striking diminution of the visible subtense of these 

 wires, when compared with the round one; and this so considerable, as could 

 not be obtained with round wires, unless they could be drawn to 2 or 3 thousand 

 to the inch. 



XII. The Case of a Patierit voiding Stones through a Fistulous Sore in the 

 Loins, without any concomitant Discharge of Urine by the same Passage. 

 By Mr. S. F. Simmons, p. 108. 



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