344 Proceedings of the Society for 'promoting 



method to the theory of escapements." It was shown, that, by the me- 

 thod here proposed, the variation from the law of a cycloidal pendulum 

 might be determined with great ease and simplicity, whether produced by 

 resistance, friction, impulse, or any other cause. By taking, as examples 

 of the method, the different escapements of clocks and watches which have 

 been invented, it appeared that the relative goodness of them, as resulting 

 from the calculation, was very nearly that which they are found to possess 

 in practice. Professor Airy also proposed a clock-escapement which would 

 possess the advantages of the detached escapement in watches, and could 

 never be out of beat. 



Mr Whewell gave a short account of the experiments undertaken by 

 Mr Airy and himself in Cornwall, for the purpose of discovering the 

 earth's density. The process employed consisted in determining the re- 

 lative rate of a detached pendulum of Kater's construction at the earth's 

 surface, and at a point 1200 feet below it, in the mine of Dolcoath. The 

 undertaking was left incomplete in consequence of the destruction of one 

 of the pendulums employed during its conveyance from the bottom of the 

 mine to the top. 



December 11. — A paper was read by Mr Peacock " on the numerals of 

 the South American languages." The most complete of these systems of 

 numerals proceed according to the vicenary scale, which has, generally, 

 the denary and quinary subordinate to it. Others of these languages are 

 remarkable for not having more than three or four words properly expres- 

 sing numbers ; and one instance was given in which the name for one is 

 the only independent numeral. 



Professor Airy gave an account, illustrated by drawings, of the steam- 

 engine as it is used in Cornwall, describing some artifices in its employ- 

 ment which are peculiar to that district, and in particular the machinery 

 by which it is applied to the drainage of the mines. 



3. Proceedings of the Society for Promoting the Useful Arts in Scotland. 



December 1, 1825. — Dr Hibbert read a Paper " on the productiveness 

 of the Cod Bank to the west of the Shetland Isles." At the same meeting 

 there was read a Paper by Mr John Henderson, Brechin Don, " on the 

 Burning of Smoke, with plans of improved furnaces for that purpose." 



January 18, 1826. — The following Papers were read : — 



1. Account of a New Life Boat by Mr John Henderson. 



2. Observations on the History of Life Boats by Professor Wallace. 



3. Description of a Simple Punt Boat for saving time and labour, by 

 Andrew Waddell, Esq. See this Journal, No. viii. p. 338. 



January 24. — There was read M An Account of a New Eye-tube for a 

 Sextant by Mr Adams, A. M." See this Journal, No. vii. p. 95. 

 February 21. — The following Papers were read:— 



1. A notice of an Improved Furnace Chimney, by Robert Bald, Esq. 

 was read. 



2. Notice of a method of producing an Intense Heat from Gas for va« 

 rious purposes in the Arts, by Dr Brewster. 



3. Dr Duncan jun. exhibited the method which he had long used of 

 obtaining great heat from coal gas. 



