Proceedings of the Boyal Scottish Society of Arts. 381 



1. An apparatus to be occasionally attached to a Turning-Lathe with a 

 short slide, to fit it for cutting Screws of the whole length of the bed of tha 

 Lathe, was exhibited by Sir John Robison, K.H., F.R.S.E., P.R.S.S.A. 

 Thanks voted to Sir John, who was requested to give a written descrip- 

 tion to bo printed. Referred to a Committee. (^^\ 



Sir John Robison submitted to the meeting this apparatus, which being 

 attached to a slide-rest lathe, fitted it for cutting screws of a considerable 

 variety of pitches, and of any length the lathe could take in. 



The apparatus differed from the usual constructions in having only four 

 pairs of toothed wheels, and in only one pair being used at a time, thus 

 doing away the risk of error by the introduction of wrong intermediates. 

 Another variation from the ordinary constructions appeared in the mode of 

 connecting the leading screw of the slide-rest with the wheel-work, which 

 was in this case effected by a square rod sliding in a tube, and adjustable 

 at any required length ; the connection was terminated at each end by an 

 universal joint, by means of which the cutter-holder of the rest was free 

 to advance and retreat sufficiently for executing the work. 



Sir John explained, that, by limiting the number of change-wheels to 

 four pairs, a considerable simplification is obtained ; while, as the four 

 pairs afford seven permutations (as either wheel of each pair maybe made 

 the driver) a sufficient variety of pitches for all the ordinary wants of the 

 workshop may be obtained by a few changes of leading screws in the ap- 

 paratus on the table ; the addition of a leading screw of 10 turns, and one 

 of 36 turns per inch to the ordinary screw of the rest (which has 12 turns) 

 gives 21 pitches, varying from 3^ turns to 108 turns per inch — and these 

 pitches may be either of right or left hand threads. 



2. Sir John Robison also exhibited specimens of Sheet-Glass (white 

 and coloured), perfectly flat, and without cockle or wrinkles ; from Messrs 

 Chance's glass-works, Birmingham. Thanks voted. n^\ 



3. A Working Model of his Patent (Piston) Rotary Steam-Engine was 

 exhibited in action. By Chjirles Cameron, Esq. F.R.S.S.A." Thanks voted. 



4. Specimens of a Bituminous Substance found in crevices where a 

 Dike occurs in the sandstone of Binny Quarry, and of Candles made from 

 it, were exhibited. By Mr William Hogg, quarrier, XJphall. Thanks 

 voted. /5^^ 



5. Sir John Robison exhibited a Model of Wood Paving, now being 

 tried in Paris, made from small trees. Thanks voted. r^\ 



The following Reports of Committees were read and ap- 

 proved of, viz. — 



1. On Mr Mcikle's Muted Clarionet. Mr R. Hunter, Convener. (844.) 

 2 On Mr Maxton's Stopper for Winding-Engines, Mr D. Stevenson, 

 Convener. (835.) 



VOL. XXXV. NO. LXX. OCTOBER 1843. 2 C 



