228 Analyses of 'Books. [Sept. 



II. On a remarkable Application of Coles's Theorem. By I. 

 F.W. Herschell, Esq.] This paper, beingtentirely algebraical, 

 and not susceptible of abridgement, could scarcely be made in- 

 telligible to the reader without transcribing the whole of it. 

 On that account I must refer those who are curious to know the 

 application of Mr. Herschell to the paper itself. I may only 

 observe, that the conclusions of the ingenious author apply 

 rather to the algebraic expressions than to the conic sections 

 themselves. 



III. Observation of the Summer Solstice 1812, at the Royal 

 Observatory. By John Pond, Esq. Astronomer Royal, F R.S.] 

 From this observation, made with the new mural circle, with 

 more accuracy, Mr. Pond informs us, than any former instru- 

 ment was susceptible of, the obliquity of the ecliptic comes out 

 23° 27' 52"25". 



IV. Observations relative to the Near and Distant Sight of 

 different Persons. By James Ware, Esq. F.R.S.] This curious 

 paper contains a great many cases of near-sighted persons, with 

 remarkable changes produced in the sight by different causes. 

 These cases authorize the following conclusions: — 



1. Near sightedness is rarely observed in infants, or even in 

 children under ten years of age. It affects the higher classes of 

 society more than the lower : and the instances are few, if any, 

 in which, if the use of concave glasses has been adopted, in- 

 creasing years have cither removed or lessened this imperfection. 



2. Though the usual effect of time on perfect eyes be that of 

 inducing a necessity to make use of convex glasses, in order to 

 see near objects distinctly, yet sometimes, even after the age of 

 fifty, and after convex glasses have been used many years for 

 this purpose, the eyes have not only ceased to derive benefit from 

 them, when looking at near objects, but they have required 

 concave glasses to enable them to distinguish with precision 

 objects at a distance. 



3. Though the caus« of this change be not always known, yet 

 sometimes it has been induced by the use of evacuating reme- 

 dies, particularly of leeches applied to the temples ; and some- 

 times by looking through a microscope, for a continued length 

 of time, for several successive days. 



4. Instances are not uncommon in which persons far advanced 

 m life (viz. between eighty and ninety), whose eyes have been 

 accustomed for a long time to the use of deeply convex glasses, 

 when they have read or written, have ceased to derive benefit 

 from these glasses, and they have become able, without any 

 assistance, to see both near and distant objects almost as well as 

 when they were young. Although it be not easy to ascertain the 

 cause of this amended vision, it seems not improbable that it is 

 occasioned by an absorption of part of the vitreous humour : iu. 



