\'0L. VII.] PHILOSOPHICAL TRANSACTIONS. 703 



III. A Philosophical Essay, declaring the probable causes of stones in the 

 greater world, in order to find out the causes and cure of the stone in the kid- 

 neys and bladder of men ; by D. Thomas Sherley, physician in ordinary to his 

 majesty, Londini, in 8vo. 



Contains nothing worth notice. 



IV. Caroli Claroniontii, M. D. &c. de Acre, Solo, et Aquis Angliae, deque 

 Morbis Anglorum vernaculis Dissertatio: Nee non Observationes Medicae 

 Canibro Britannicas. Londini, 1672, in I'Zmo. 



Ill the first of these tracts, the author gives an account of the situation, air, 

 soil, and waters of England: as also of the temper, diet, exercises, and chief 

 sicknesses of the inhabitants thereof; in the other, he delivers several histories 

 of diseases, managed by himself in Wales, describing the nature of each dis- 

 order, with the treatment and termination thereof. 



Mr. Neifton's Letter to the Editor, of March 26, 1672, containing 

 some more Suggestions about his new Telescope, and a Table of 

 Apertures and Charges for the several Lengths of that Instrument. 

 N" 82, p. 4032. 



Sir, — Since my last letter I have further compared the two telescopes, and 

 find that of metal to represent, as well the moon as nearer objects, something 

 more distinct than the other; but I am not well assured of the goodness of 

 that other, which I borrowed to make the comparison; and therefore desire 

 that the other experiment should be rather confided in, of reading at the dis- 

 tance of between 100 and 120 feet, at which I and others could read with it in 

 the Transactions, as I found by measure; at which time the aperture was l-i- of 

 an inch, which I knew by trying, that an obstacle of that breadth was requisite 

 to intercept all the light which came from one point of the object. 



I should tell you also, that the little plain piece of metal, next the eye-glass, 

 is not truly figured, whereby it happens that objects are not so distinct at the 

 middle as at the edges. And I hope that by correcting its figure, (in which I 

 find more difhculty than one would expect) they will appear all over distinct, 

 and more distinct in the middle than at the edges. And I doubt not but that 

 the performances will then be greater. 



But yet I find that there is more light lost by reflection of the metal which I 

 have hitherto used than by transmission through glasses, for which reason a 

 shallower charge would probably do better for obscure objects, suppose such a 

 one as would make it magnify 34 or 32 times. But for bright objects at any 

 distance, it seems capable of magnifying 38 or 40 times with sufficient distinct- 



