HISTORY OF COLD AND THK ABSOLUTE ZERO. 209 



cold 1)0 ii |)(^sitiv(> (|Uiility or hut :i pii\ ativc it will be needless to con- 

 tend Avhiit particular l)od\M)uoht to be esteemed the primuni frioiduni." 

 The whole elal)orate investigation cost Boyle immense labor, and he 

 confesses that he '"never handled any part of natural philosophy that 

 was so troublesome and full of hardships." He looked upon his 

 results l)ut as a "l)eginning'"' in this held of incpiiry, and for all the 

 trouble and patience expended he consoled himself with the thought 

 of "'men being oftentimes obliged to sutler as much wet and cold and 

 dive as deep to fetch up sponges as to fetch up pearls." After the 

 masterly essay of Boyle the attention of investigators was <'hieiiy 

 directed to improving thermometrical instruments. The old air ther- 

 mometer of Galileo being inconvenient to use, the introduction of 

 Huid thermometers greatly aided the inquiry into the action of heat 

 and cold. For a time great difhculty was encountered in selecting 

 proper tixed points on the scales of such instruments, and this stinui- 

 lated men like Huygens, Newton, Hooke, and Aniontons to suggest 

 remedies and to conduct experiments. By the beginning of tlie eight- 

 eenth century the freezing point and the boiling point of water were 

 agreed upon as tixed points, and the only apparent dithculties to be 

 overcome were the selection of the fluid, accurate calil)ration of the 

 capillary tube of the thermometer, and a general understanding as to 

 scale divisions. It must be confessed that great confusion and inac- 

 curacy in temperature observations arose from the variety and crudc- 

 ness of the instruments. This led Amontons in 1702-3 to contribute 

 two papers to the French Academy which reveal great originality in 

 the handling of the subject, and wdiich, strange to say, are not gener- 

 ally known. The hi'st discourse deals witli some new proptM-ties of 

 the air and the means of accurately ascertaining the temperature in 

 any cliuiate. He regarded heat as due to a movement of the j)articles 

 of ))odies, though he did not in any way specify the nature of the 

 motion involved, and as the general cause of all terrestrial motion, so 

 that in its al)sence the earth would be without movement in its smallest 

 parts. The new facts he records are observations on the s})ring or 

 pressure of air brought about ])v the action of heat. He shows that 

 different masses of air measured at the same initial s])ring or pi-es- 

 sure, when heated to th(> l)oiling point of water, acquire <Mjual incre- 

 ments of spring or pressure, provided the \olume of tlu^ gas ]k\ kept 

 at its initial value. Further, he proves that if the ])ressure of the 

 gas before heating be doubled or tripled, then the additional s[)ring 

 or ])ressure resulting from heating to the boiling |X)int of water is 

 equally doubled or tripled. In other words, the ratio of the total 

 spring of air at two definite and steady temperatures and at con- 

 stant volume is a constant, independent of the mass or the initial 

 pressure of the air in tlie thermometer. These results led to the 



SM 1903 U 



