38 PHILOSOPHICAL TRANSACTIONS. [aNNO 1684. 



for if the substance came out straight, then there were always hairs; but if 

 bended none. 



In the year 1674, I asserted that the cuticula, or upper skin of a body, con- 

 sists of round particles or scales. I then saw by a common microscope the parts 

 of the scales appearing to the eye as if they were round, lying close in order, 

 and so small that a sand would cover 200 or 250 of them. But examining 

 them since by a glass which magnifies more, I am satisfied that they are not 

 made out of the grosser part of the moisture or substance which is evaporated 

 out of the body, as I formerly thought, but are mere scales, such as grow on 

 the outward skin of a fish, and called fish-scales. These scales lie on our body 

 just as they do upon fishes, the most part of them are five-sided, and are very 

 thin, for I judge their breadth is above 25 times more than their thickness. 

 They lie three deep on the body, every part being covered with 3 scales suc- 

 cessively, though not above i- part of a scale discovers itself to the eye, the 

 other 4- parts being hid by the other scales. 



The scales of fishes also appear but in part to the eye ; but it is very remark- 

 able, that though fishes never change their scales, yet men do often ; particu- 

 larly I instance in myself at this time, being the 1st of September, that the 

 scales came off me not one by one, but 1000 in a cluster. When I pluck off a 

 scale from my body which sticks fast, and perhaps is but newly grown, there 

 comes blood after it, or at least there remains a red spot. 



It is easy to conceive how a louse, flea, or other insect may thrust his sting 

 or snout into the skin ; for they need not do it through the scales, but between 

 the plates or mails. From hence also may be perceived, that there are no 

 pores in the cuticula, for the conveying out of sweat, because that may ouze 

 out from between the scales, though they stick never so close together, with- 

 out supposing that there are channels made for its passage. Let us only reckon 

 how many vacuities a scale has, whereby it is nourished so as to grow, and that 

 in the space of 4- part of a scale there may be 100 such vacuities, through 

 which the humours of the body may pass, and that 200 such parts of a scale 

 may be covered with a sand. It will follow then, that the body may exhale out 

 of 20,000 places in a quantity no larger then what a sand will cover. 



j4 Letter from Mr. John Collins, to Dr. John fVallis, Savilian Professor of 

 Geometry in the University of Oxford, respecting some Defects in jilgebra. 

 N° 159, p. 575. 



To describe the locus of a cubic equation. 



A Cardanic equation convenient for the purpose, viz. such as shall have the 



