8 Sketch of the ImprovemeiHs in Science [Jan. 



account of both these instruments has been given in the preceding 

 voUimes of the Annals of Philosophy. 



Dr. Young's eriometer is founded upon a different optical prin- 

 ciple, but is not less ingenious. His ovvn account of it, and many 

 curious measurements made by it, will be found iti the Annals of 

 Philosophy, vol. ii. p. 115. 



Mr. Ware's paper on the near and distant sight of persons, 

 together with Sir Charles Blagden's appendix to it, both published 

 in the Philosophical Transactions for 1813, will prol)ably be consi- 

 dered as more closely connected with medicine than with optics. 

 He has shown that near-sightedness depends in a great measure 

 upon the peculiar habits of the person, that it is particularly 

 brought on by literary pursuits, that it is increased by the use of a 

 concave glass, and that it is not apt to diminish as the short sighted 

 person advances in life. 



IV. Hydrology. 



The most remarkable hydrological improvements of the year are 

 the hydraulic machines of M. Mannoury Dectot, of vvliich an 

 account has been given in the Annals of Philosophy, vol. i. p. 183, 

 and vol. ii. p. 41 2. Tiiese curious machines are, the Intermitting 

 Syphon, the Hydreole, the Oiciilating Column, and the Da-r 

 naide. The oscillating column is the contrivance which displays 

 the greatest originality; but the Danaide seems to he tiie best 

 adapted for a mechanical moving force, and might be used in cer- 

 tain circumstances with obvious advantage, 



Mr. Gough's explanation of the mechanism of Ebbing and 

 Flojvifig Wells, which appeared in the 2d volume of the Man- 

 chester Memoirs, publisl;ed in 1813, is entitled to the praise of 

 novelty, and seems perfectly satisfactory. He ascribes the inter- 

 ruption in the regular flow to a quantity of air whijeh occasionally 

 mixes with the water, and partly choaks up the passage. 



It mav be worth while to notice some other hydraulical inventions 

 wliich have been made known to the public in the course of the 

 last year. 



Mr. Brunton's pump for raising water from wells or mines while 

 sinking is certainly an improvement ; but as it would require a long 

 description to make tlie improvement completely understood, wc 

 shall satisfy ourselves with referring to the Transactions of the 

 Society of Arts for 1812, or to Nicholson's Journal, vol. xxxiv. 

 p. G4, where it is copied from the first mentioned book. 



For the same reason we refer to Nicholson's Journal, vol. xxxiv. 

 p. 335, for a description of Mr. Woodhouse's perpendicular lift, 

 employed as a substitute for a lock on the Birmingham and Vv or- 

 cester canal at Tardebig. 



V. Mechanics^ 

 Mr. Peter Ewart, of Manchester, has published a most alile 

 defence of the opinion adopted by Leibnitz and his disciples, that 



