Royal Soctetij. 377 



structed gas-works for lighting Dumfries, in 1825, I had the 

 burners made on the plan I have described ; and experience 

 has shown that they answer the purpose of requiring less 

 gas than other burners, and giving at the same time as bril- 

 liant, and perhaps a more beautiful flame- Nor have I from 

 any subsequent experiment found any cause for adopting a 

 different construction. To alter the burners of a whole town 

 would, however, be an expensive and troublesome process; 

 yet in making the burners for Greenock (which town I have 

 lighted within the last six months), I had an opportunity of 

 introducing any improvement, had I seen occasion to alter the 

 principle 1 had formerly adopted for Dumfries. 



I am. Gentlemen, yours, &c. 

 Greenock, March 10, 182!). WiLLlAM LowRY. 



LVII. Proceedings of Learned Societies. 



ROYAL SOCIETY. 

 Dec. 11th. — A paper was read, intitled, "On a method of com- 

 paring the light of the sun with that of the fixed stars." By William 

 Hyde Wollaston, M.D. V.P.R.S. &c. 



In the Philosophical Transactions for the year 1767, a suggestion 

 is thrown out by Mr. Michell, that a comparison between the light 

 received from the sun and any of the fixed stars might furnish data 

 for estimating their relative distances ; but no such direct comparison 

 had been attempted. Dr. Wollaston was led to infer, from some ob-' 

 servations which he made in the year 1799, that the direct light of the 

 sun is about one million times more intense than that of the full 

 moon, and therefore very many million times greater than that of all 

 the fixed stars taken collectively. In order to compare the light of 

 the sun with that of a star, he took as an intermediate object of com- 

 parison tiie light of a candle reflected from a small bulb about a 

 quarter of an inch in diameter, filled with quicksilver, and seen by 

 one eye through a lens of two inches focus, at the same time that the 

 star or the sun's image, -placed at a proper distance, was viewed by the 

 other eye through a telescope. The mean of various trials seemed to 

 show that the light of Sirius is equal to that of the sun seen in a glass 

 bulb one-tenth of an inch in diameter, at the distance of 210 feet ; 

 or that they are in the proportion of one to ten thousand millions: 

 but as nearly one-half of the light is lost by reflection, the real pro- 

 portion between the light from Sirius and the sun is not greater than 

 that of one to twenty thousand millions. If the annual parallax of 

 Sirius be half a second, corresponding to a distance of .')'2.^,481 times 

 that of the sun from the earth, its diameter would be 37 times that of 

 the sun, and its light \'.VH times as great. The distance at wliirh the 

 sun would require to be viewed so that its brightness miglit be only 

 equal to that of Sirius, would be 141,421 times its present distance; 

 and, if still in the ecliptic, its annual parallax in longitude would be 

 N. S. Vol. 5. No, 29. Mot/ 1829. 3 C nearly 



