126 Selections from the Correspondence of 



them, ready brought forth to their hands, and to which we are 

 great strangers ; but because you see them every day, they are 

 thought common and not worth notice. 



Hitherto I have wrote only to blot paper ; but now I tell you 

 something new. Doct. Knight, a physician, has found the art 

 of giving such a magnetic power to steel, that the poor old load- 

 stone is put quite out of countenance ; his steel magnets act on 

 the needles, and transmit their power to knives, &c, as the load- 

 stone. But he has also shown a secret on the loadstone not 

 known before, by increasing its attractive power to a greater 

 degree, and can at pleasure change the poles how he pleases. 

 Take these examples : — A loadstone of a parallelopiped form he 

 made the opposite end south poles, and the middle quite round 

 all north poles. In another flat stone he made the opposite ends 

 north poles, and the opposite sides south poles. In another load- 

 stone of an irregular flat shape, he made half of each of the flat 

 surfaces a north pole, and the other half a south pole, so as that 

 the two half surfaces opposite each other, should be of a contrary 

 denomination, with many other changes and varieties, showing 

 he had the power to impress the faculty of either pole many parts 

 of the loadstone, with as much ease as a loadstone will influence 

 a needle. I am yours, P. Collinson. 



Dr. Gronovius hopes you will continue your remarks, and send 

 him seeds of any of your vegetable productions. 



The subjoined postscript to a later letter of Collinson to Dr. 

 Colden, will bring to mind the correspondence of this candid 

 man with Linnaeus on the same subject ; (vide Smith's Corres- 

 pondence of Linnaeus ; and this Journal, Yol. xl, p. 7.) 



" Dr. Linnaeus is now publishing his Species Plantarum, with 

 many new-coined names, which will so puzzle the science of 

 botany that it will be impracticable to comprehend it. The 

 Azaleas he has turned into Kalmias ; so that every book he 

 prints will require a new edition of his Nova Genera, which is a 

 grievous tax and imposition on the public." 



Mr. Collinson to Dr. Colden. 



London, June 9th, 1755. 



I cannot let this ship sail without asking you, how it fares with 

 you this troublesome time ? Your situation makes me anxious 



