DECEMBER 6, 1906 | 
NATURE 133 
Griffiths, ‘‘ On the Boiling Point of Sulphur, &c.,’’ Phil. 
Trans., 1891, the application of his method was further 
extended, and a simple method of standardisation was 
proposed. In continuation of this work Prof. Callendar 
has written a number of subsidiary papers dealing with 
details of construction of instruments, and applications to 
special purposes. The results of this thermometric work 
have since been confirmed by Chappuis and Harker, Phil. 
Trans., 1889, at the Bureau International, Paris, and by 
other observers, and are now generally accepted. : 
More recent developments in accurate electrical thermo- 
metry have been described by Prof. Callendar in later 
papers. He has also devised a special type of ‘“‘ gas- 
resistance’? thermometer, depending on the increase of 
viscosity of a gas with temperature, which is the exact 
analogue of the electrical resistance thermometer, and 
possesses peculiar advantages for high temperature measure- 
ments. 
The application of electrical resistance thermometers and 
thermo-couples to the observation of rapid variations of 
temperature has been utilised by Prof. Callendar in the 
study of the adiabatic expansion of gases and vapours, and 
in the observations of the cyclical changes of temperature 
of the steam and of the cylinder walls in a steam-engine. 
The latter research was undertaken in conjunction with 
Prof. Nicholson, with a view to elucidate the theory of 
cylinder-condensation. 
The researches of Rowland and other experimentalists 
on the specific heat of water and the mechanical equiva- 
lent of heat had shown that grave uncertainties affected 
the value of this most fundamental physical constant, 
which could not be removed satisfactorily without a com- 
plete investigation of the variation of the specific heat of 
water between 0° C. and 100° C. Prof. Callendar devised 
a continuous electrical method of attacking this problem, 
possessing many important advantages as compared with 
older methods. He was assisted by Dr. Barnes in carry- 
ing out this work, the results of which form the subject 
of papers by Callendar and Barnes in the Phil. Trans. 
Roy. Soc., to901. As an illustration of the probable 
accuracy of their results it may be observed that, whereas 
by any of the older formule accepted for the variation of 
the specific heat of water, the values of Rowland and of 
Reynolds and Moorby for the mechanical equivalent are 
seriously discordant, they are brought into perfect agree- 
ment by the work of Callendar and Barnes. 
In the subject of conduction of heat Prof. Callendar has 
contributed many original methods described in various 
minor papers, and, in addition to the thermal investigations 
with which his name is chiefly associated, has carried out 
some purely electrical researches. 
Royal Medals. 
One of the Royal medals has been awarded, with the 
approval of His Majesty, to Prof. Alfred George Greenhill, 
a fellow of the society, on account of the number and 
importance of his mathematical investigations produced 
between the year 1876 and the present time. They embrace 
a variety of mechanical and physical subjects, including 
dynamics, hydromechanics, electricity, and gunnery. He 
is the author of two treatises on hydromechanics, both 
remarkable for originality of treatment. 
The subject, however, to which he has devoted most 
time and attention is the theory of elliptic functions. His 
work on this subiect may be placed in two classes :— 
(1) Investigations in which he has extended the subject into 
new fields, as in the series of memoirs on the ‘* Transform- 
ation and Complex Multiplication of Elliptic Functions,” 
contributed to the Proceedings of the London Mathematical 
Society (vols. xix., xxi., xxv., xxvii.), and in the memoir 
on the ‘‘ Third Elliptic Integral and the Ellipsotomic 
Problem,”’ in the Phil. Trans. (vol. cciii.). (2) Applications 
to mechanical problems, mainly dynamical, for purposes 
of calculation or illustration. In this class may be placed 
his treatise on the elliptic functions, as well as numerous 
papers in journals and the proceedings of scientific 
societies. 
All Prof. Greenhill’s work is characterised by much 
originality, and by a rare power and skill in algebraic 
analysis. 
His Majesty has also approved the award of a Royal 
NO. 1936, VOL. 75] 
medal to Dr. Dukinfield Henry Scott, also a fellow of the 
society, for his investigations and discoveries in connection 
with the structure and relationship of fossil plants. Dr. 
Scott began the very important work which he has accom- 
plished in this subject by helping the late distinguished 
palzobotanist, Prof. W. C. Williamson. In this cooper- 
ation he greatly enhanced the value of Williamson’s work. 
He not only added many new discoveries, but, what was 
more important, demonstrated the value of the worl in 
relation to phylogeny. 
Dr. Scott has since added much of first-rate importance. 
He has discovered and elucidated many important types, 
his work constituting a most valuable acquisition to botany 
from the evolutionary point of view. It is not only in 
the accurate investigation of difficult structures that Dr. 
Scott has been so successful; not the least of his merits 
lies in the philosophical treatment of the problems sug- 
gested by his discoveries. His position as one of the lead- 
ing palzobotanists in the world is well recognised. He 
has, both by his personality and by his writings, exercised 
a well-marked and widespread influence on the work of 
other botanists. The fact that he has created in this 
country a vigorous school of palaobotanists may be re- 
garded as an additional claim for the honour now conferred 
upon him. 
Davy Medal. 
The Davy medal is given to Prof. Rudolf Fittig, pro- 
fessor of chemistry in the University of Strassburg, who 
began to publish scientific work as early as 1858, and in 
1864 discovered the method for the synthesis of hydro- 
carbons homologous with benzene, which has ever since 
borne his name. Up to about 1880 he worked chiefly on 
benzene derivatives, but his attention was gradually 
attracted to the study of lactones and acids, both saturated 
and unsaturated, which has largely formed the subject of 
his numerous published papers down to the present day. 
Fittig has been a remarkably active worker. The Royal 
Society Catalogue contains under his name alone ninety- 
six papers, and, jointly with students and others, seventy- 
one more down to 1883. Since that time a number about 
equally large has been recorded in the indexes of the 
chemical journals. The work of Fittig and his students 
on lactones and acids, and particularly the intermolecular 
changes which many unsaturated acids undergo, may be 
said to be classical, and it has had an important influence 
on the progress of theoretical chemistry. 
Darwin Medal. 
The Darwin medal has been awarded to Prof. Hugo 
de Vries, For.Mem.R.S. Prof. de Vries has made a series 
of important discoveries in connection with the manner in 
which new races of organisms may originate, and he has 
materially extended and systematised our knowledge of the 
laws affecting the results of hybridisation. His work is 
the outcome of very extensive experiments that have been 
carried on for many years. He has stimulated numerous 
investigators, both in Europe and in America, to extend 
these inquiries, and the results already obtained are of 
great importance, both from a theoretical and from a prac- 
tical point of view. De Vries’s work has exercised con- 
siderable influence on other branches of biology, and has 
suggested new lines of investigation in many directions. 
Hughes Medal. 
Mrs. W. E. Ayrton is the recipient of the Hughes medal, 
which is awarded for original discovery in physical sciences, 
particularly electricity and magnetism, or their applications. 
Her work on the electric arc has been described in a paper 
published in the Philosophical Transactions, and in various 
other publications. 
Mrs. Ayrton’s investigations cover a wide area. She 
discovered the laws connecting the potential difference 
between the carbons of an arc with the current and with 
the distance between them, and proved these to apply, not 
only to her own experimental results, but to all the pub- 
lished results of previous observers. Dealing with the 
modifications introduced into the are by the use of cores 
in the carbons, she found the causes of these modifications. 
The peculiar distribution of potential through the arc was 
traced, and its laws were discovered by her. 
