364 Mr. Herapath on True Temperature, and the [Nov. 



indeed I have not near time to consider as they deserve, and, 

 therefore, fear many beautiful phenomena connected with them 

 I shall be obliged to leave untouched. 



By his theory, it appears that ebullition and evaporation are 

 distinct and separate phenomena, both indeed depending on the 

 same cause, temperature, or the violence of collision, but the one 

 influenced by a circumstance, namely superincumbent pressure, 

 which has no effect on the other. For want of attention to this 

 distinction some writers, and among them the Rev. Dr. Wollaston, 

 have run into considerable errors. The Doctor, following the hints 

 and example of the Spanish philosopher Betancourt, has endea- 

 voured to contrive, by the temperatures of ebullition, and a ther- 

 mometer which he terms a barometrical thermometer, a method 

 of determining the heights of elevations. A very important con- 

 sideration, however, having been overlooked by the latter, and 

 not noticed by the former, renders the method, as it is now em- 

 ployed, scientifically incorrect. But I shall have presently to speak 

 of this subject. My object is now to develop from physical consi- 

 derations the mathematical laws of evaporation, that we may see 

 by their accordance with phenomena whether the simple opera- 

 tions of nature, rationally investigated, will not enable us to dis- 

 cover and establish something in the shape of a probable and 

 a consistent theory. 



Dejinitions. 



In consequence of the new and enlarged views I have taken, 

 I have found it necessary to make an alteration in the term 

 numeratom I have hitherto employed, and to introduce some 

 new ones. I have already expressed my aversion to making 

 innovations, and certainly disapprove of the introduction of new 

 terms where it can be avoided ; but in the present instance where, 

 by pursuing the route of Newton, I have departed so far from the 

 beaten track, I cannot see how I can conveniently do without it. 

 However, I have been as sparing as possible ; and though I 

 employ the following terms, 1 shall be very ready to change them 

 for any which may be thought more suitable or proper. Some 

 of those defined I may, perhaps, not want in the course of my 

 present inquiries ; but I thought it better to introduce them at 

 once on account of their analogy and affinity to the others. 



Def. 1. — Numeratomum, derived from numenis, a number, and 

 the genitive plural atomorum, of atoms, I intend to signify the 

 number of atoms in a specified space, without regard to the 

 equality of magnitude in the atoms, or uniformity of figure. 



DeJ. 2. — Arithmeridone, derived from dpi^oc, number, and 

 the genitive plural ,u£pi3wv, of particles, signifies also the number 

 of particles in a specified space, without any regard to their 

 equality or similarity. 



DeJ. 3. — Voluminatom, from voluminis, of volume, and atomi, 

 atoms, denotes the number of atoms in a unity of volume. 



