5t) PHILOSOPHICAL TRANSACTIOIfS. [aNNO 1744. 



bodies are always transparent, so the epidermis is transparent enough, to show 

 any colour reflected from the parts below it: so that we must consider the epi- 

 dermis of white people as a transparent pellicle, of too subtile or rare a substance, 

 and too minutely divided, to reflect any rays of light from its surface ; but con- 

 sisting of numbers of pores, which readily transmit those lays through its thin 

 and rare substance, by which it shows the colour of whatever parts are below it ; 

 on which the colour of white people depends. 



But, as there are numbers of scales, or several strata of scaly lamellae in the 

 epidermis, so this transmission of the rays of light, from the subcutaneous parts, 

 must be imperfect, some of these rays being intercepted in passing through the 

 several lamellae; and the thicker the cuticle is, i.e. the more there are of these 

 lamellae, or the denser their texture, the more the light will be intercepted in 

 passing them, and the more the colour of the skin will degenerate from the pure 

 white of the membranes below it. This is agreeable to experience; for Mr. 

 Cowper tells us, in his anatomy, that the thickness of the skin proceeds from 

 the number of the strata or layers of scales which compose it; and we may daily 

 observe that those who have such thick and coarse skins, are never of so perfect 

 and pure a white, as those who have a thin and fine skin, as Cowper observes. 

 But the reason why such thick skinned people appear of a yellowish or tawny 

 colour will be plain, from Newton's observations. Opt. lib. 2, p. 1, obs. 9 and 20; 

 where he shows a faint yellowish colour to be the one that proceeds from an im- 

 perfect transmission of a white; for no one can say, but that both the internal 

 membranes and humours of such swarthy people are of the same colour in time 

 of health, with those of the perfectest white skins, as well as they are in 

 Negroes. And this seems to be the cause of the pale yellow of dead bodies, 

 whose skins are not perspirable, and consequently not so transparent, as in a liv- 

 ing subject. 



From this account of the cause of the difference in colour among those people 

 that are white, we may account for the cause of the colour of Indians, and other 

 tawny people, who seem to differ from each other in colour, and from white 

 people only in degree, as they have more or less of this tawny yellow proceeding 

 from the imperfect transmission of a white in their colours : thus, if we proceed 

 from the swarthiest white person to the palest Egyptian, from thence to the fairest 

 Mustee, Mulatto, Moor, &c. to the darkest Indian, we may plainly see, that 

 they differ from each other only as they have more or less of the original white 

 in their colour; and as we have shown this tawny colour in white people to pro- 

 ceed from the thickness or density of their skins, obstructing the transmission of 

 the rays of light; so it is very plain that the same tawny colour, in these other 

 tawny people, which seems to be of the same kind, but different in degree, must 

 proceed from a like cause, that is, the thickness or density of their skins; and 



