046 Scientific Proceedings, Royal Dublin Society. 
to place in the hands of the investigator a means of testing the 
adequacy of material theories. Beyond this, it is needless to 
observe, are ranged a host of problems awaiting solution in a 
dynamic conception of matter. ‘To open this gateway of knowledge 
and reveal the light within, Prof. Preston has laboured earnestly 
and effectively. 
We have in the foregoing referred to Professor Preston’s lead- 
ing work and to that specially qualifying him to receive the Boyle 
Medal, but before this work appeared, he was already known as a 
writer on science of high standing. His text-books on Light and 
Heat (“Theory of Light,” Macmillan, 1890, 2nd. ed. 1890; 
‘Theory of Heat,’ Macmillan, 1894) are at once characterised by 
a clear and pleasant style and a thorough grasp of the subjects 
treated. These works may each fairly claim to be advances on any 
previous English text-books of the same scope. ‘The classical 
experiments of the earlier and central years of the century find 
sufficient notice, but are not given that undue prominence which 
detracts from the value of many text-books. ‘The methods and 
precautions of Regnault and his school should be known to all 
students in their essential features, but the science student of to- 
day possesses agents and materials to aid him in his researches 
unknown to the preceding generations. Not only have these 
been given due prominence in Professor Preston’s works, but 
they are accompanied by such able expositions of theoretical: 
principles as render these text-books of more value to the modern 
student than perhaps any other works of the kind at present 
before the public. 
Professor Preston is also the author, in part, of a well-known . 
text-book on “Spherical Trigonometry ” (Macmillan, Parts I. and 
II., 1885, 1886), as well as of several scientific papers which in 
this brief notice need only be referred to by title, but which are all 
marked by his ingenuity and thoroughness :— 
‘* Application of the Parallelogram Law in Kinematics.’’—Proc. R.D.S., VIII., 
1893-98, p. 469. 
“On the Inversion of Centrobaric Bodies.’>—Proc R.D.S., V., 1886-87, p. 639. 
‘*A Lecture Note on the Relation of the Theorem of Work to the Theorem of 
Moments.’’ —Proc. R.D.S., VIII., 1893-98, p. 167. 
“On the Continuity of Isothermal Transformation from the Liquid to the Gaseous 
State.’’—Trans. R.D.S., VI., 1896-98, Ser. II., p. 119. 
‘¢On the General Extension of Fourier’s Theorem.’’—Phil. Mag., vol. 43, 
1897, pp. 281 and 468. 
