Mr Clark on Cutting Screws. 275 



principal substances which afford a supply of fuel to the vo- 

 racious appetite of Wingen, I beg to observe that I found 

 fragments of that mineral in the bed on the Kingdom Poas^ 

 about seven miles from the mountain. The neighbouring 

 country is evidently a coal formation. This mineral has been 

 found on Colonel Dumaresk's estate, at St Hiliars; at Mr 

 Ogilvie"'s, at Merton ; at Bengala, Captain Wrighfs ; at Dr 

 Bowman's, on the Tay brook ; at Mr Glenn ie's, on the Fal- 

 brook ; at Mr Scott's on the Westbrook ; besides, in great 

 abundance, at Newcastle and Lake Macquarie, on the shore, 

 of which latter locality a very fine layer of excellent cannel 

 outcrops from beneath that of the common description. 



*' Earthquakes are, we know, of frequent recurrence in vol- 

 catiic countries ; and if we refer to the almanack of the late 

 lamented editor of the Sydney Gazette, we shall find that 

 shocks have been felt in Australia several times since the first 

 settlement of the colony. In the years 1788, 1800, 1804, 

 and 1806, such are recorded. And on the 30th of October 

 of last year, the sky being lurid, and the atmosphere sultry, a 

 loud report, like the discharge of heavy ordnance, was heard 

 at Paramatta, East Creek, Prospect, and Sydney, in a di- 

 rection from north to south. A similar report was also heard 

 at Paramatta about two years ago ; and I was credibly in- 

 formed that a tremendous noise, resembling the sudden spring- 

 ing of a mine, was noticed in the neighbourhood, and from 

 the direction of the burning mountain, previous to its dis- 

 covery in 1828." 



Art. XIV. — Description of a Method of Cutting Screws, 

 with drawings of the apparatus employed.^ By James 

 Clark, Steeple Clock and Machine Maker, Old Assembly 

 Close, Edinburgh. Communicated by the Author. 



The method of making screws which I am now about to de- 

 scribe, is the best which has suggested itself in the course of 

 thirty years experience, and combines simplicity with great 

 accuracy. 



• The Gold Medal of the Society of Arts for Scotland was given to Mr 

 Clark for this communication and relative drawings, 17th June 1829. 



