[ r 3& ] 
the Caufe of Negroes, becaufe fevcral Nations of 
People, in the fame Latitude with rhe Negroes in 
Africa , arc not made black by it. 
The Caufes of this Diverftty may be referred to 
two Heads j viz. i. The Nature and Temper of the 
Country. 2. The Ways of Living in it. Under the 
firft may be included the following Particulars : 
i. The Nature of the Soil, and Situation of the 
Country, with regard to Mountains, Waters, &c. 
which very much alter the Power of the Sun’s Heat ; 
for the differing Degrees of Heat and Cold, in dif- 
ferent Places, depend, in a great meafure, upon the 
Accidents of the Neighbourhood of high Mountains, 
whofe Height exceedingly chills the Air brought by 
the Winds over them j and of the Nature of the Soil, 
which varioufly retains the Heat, particularly the 
fandy ; which, in Africa, Arabia , and generally 
where fuch fandy Deferts arc found, do make 'the 
Heat of the Summers incredible to thofe who have 
not feit them ; as the learned Dr. Halley has re- 
marked. Whence it will appear, that the Heat or In- 
fluence of the Sun is not always the fame in the fame 
Latitudes, as they imagine who ftart this Objection 
to this Propofltion ; but that in Africa , where the 
People are black, the Soil is as intemperately hot 
as the Climate, occafioncd by the fcorching Heat of 
its Sands, according to the juft Account of Lucan , 
per calidas Libyae fitientis arenas > 
agreeable to the Accounts of all Travellers and Hifto- 
rians,efpecially thofe who talk of its inland Parts, where 
People firft began to turn black. This Heat of the Soil 
muft much increafc rhe Heat of the Sun, and its Power 
upon the Body : And if the Sun is the Caufe of 
Black- 
