roL. XVII.3 PHILOSOPHICAL TRANSACTIONS. 505 



sand, and that each scale may have many pores on the sides, besides the places 

 where it is to be nourished ; we may conclude the whole skin to be only as one 

 continued pore. 



I examined some of those scales on the inside of my hand, where the skin 

 was thickest, and found that they differed from the others only in that they 

 were thicker, and beset with many globules and stripes; but those on the body 

 are clearer; and as those on the body peel and fall off for nourishment, those 

 on the inside of the hand, by reason of a great quantity of clammy matter, 

 driven out through the skin, are fastened to one another, so as to make 

 a callous substance. Labour and working likewise forcing out a greater quantity 

 of this glutinous matter. 



On the Expansion and Contraction of Fluids by Heat and Cold, in Order to 

 ascertain the Divisions of the Thermometer, and to make that Instrument, 

 in all Places, without adjusting by a Standard. By Mr. Edm. Halley, S. R. S. 

 N° 197, p. 650. 



Qualities, such as heat and cold, moisture and dryness, and the like, are 

 not otherwise to be estimated, but by their effect on the magnitude of some 

 body they act on, by increasing or lessening its dimensions: or else by the 

 motions they produce; both which subject them to mensuration. But it is still a 

 question, how to ascertain the proportional heat or cold, &c. that is between any 

 two climates or seasons, so as to conclude the one, for example, twice as hot, or 

 twice as cold, as the other, though the instruments now in use abundantly suffice 

 to show when the temper of the air is the same, and when it is warmer or cooler. 

 The reason is, that we know not the causes of the expansion of fluids by heat, 

 or of their contraction by cold, as arising from the nature of their constituent 

 parts, which are so far from being objects of our senses, that they even surpass 

 our most refined reasonings, and extort a confession of our ignorance after all 

 our endeavours. For the same degree of heat does not proportionally expand 

 all fluids; some swelling with a gentle warmth, and others not till they be con- 

 siderably hot; some boiling with a moderate heat, and others not at all; some 

 capable of great expansion, others increasing very little ; so that it may well 

 be concluded, that no one of them increases and diminishes in the same pro- 

 portion with the heat, and consequently, that the thermometers graduated by 

 equal parts of the expansion of any fluid, are not sufficient standards of heat 

 or cold. This will be more evident from the experiments which I made some 

 time since, with water, mercury, and spirit of wine, wherein the following 

 particulars were very remarkable. 



TOL. III. 3 T 



