6 INA TOR 
[ NovEMBER I, 1906 
(Cambridge : 
Ltd., 
Technical Thermometry. Pp. ix+62. 
The Cambridge Scientific Instrument Co., 
1906.) 
Tuts pamphlet contains detailed, illustrated descrip- 
tions of the various types of instruments for tempera- 
ture measurement made or sold by the Cambridge 
Scientific Instrument Co., which has long been in 
the front rank in the manufacture of electric thermo- 
meters of all kinds. 
It deals first with the well-known platinum resist- 
ance thermometers of the Callendar-Griffiths type. 
These are made in many different forms. Among the 
most interesting of the apparatus used in connection 
with them is the ingenious direct-reading temperature 
indicator, which gives without any calculation the 
direct centigrade or Fahrenheit temperature on the 
air-scale, with a sensitiveness of considerably less 
than r° up to 1200° C. The various types of resist- 
ance-boxes used in accurate platinum thermometry 
are all arranged to be capable of self-verification. We 
believe that this self-testing type of resistance-box was 
among the first examples of a high-class physical 
instrument intentionally arranged by the makers to 
encourage periodical standardisation by the user 
rather than complete dependence upon the original 
adjustment. The Callendar recorders, in their various 
forms, can now be made to give with very low energy 
consumption continuous records of resistance, tempera- 
ture, radiation, E.M.F., current or power within very 
wide limits. 
Among the thermoelectric appliances is a new form 
of recording millivoltmeter, in which the galvanometer 
boom is depressed every half minute on to an inked 
thread, thereby leaving a dotted record on the paper. 
The instrument can be made sufficiently sensitive for 
recalescence curves. The radiation pyrometers of 
Prof. Féry are also described and illustrated. In 
these the radiation from the object the temperature 
of which is to be measured is concentrated upon a 
minute thermocouple at the focus of a mirror or lens, 
and the E.M.F. set up is measured in the ordinary 
way by a suitable millivoltmeter. : 
In an appendix are given an excellent summary of 
the principles of electric thermometry with tables of 
constants, and a list of trustworthy melting and boil- 
ing points obtained from the National Physical Labor- 
atory; also a good bibliography of recent thermal 
research. 
Astronomischer Jahresbericht. Band vii. Literature 
of 1905. By A. Berberich. Pp. xxxvii+646. 
(Berlin: Georg Reimer, 1906.) Price 20 marks. 
Tuis volume is the seventh issue of a series of most 
useful compilations, and it is a matter of deep 
regret that the founder and chief worker of such an 
admirable publication is no longer with us. Herr 
Walter Friedrich Wislicenus died last year on 
October 3, but, as we are told by Dr. Walter de 
Gruyter in a brief obituary notice, he contributed a 
considerable portion of the present volume. The 
frontispiece to this issue, therefore, fittingly presents 
us with an excellent portrait of the founder, whose 
place is now taken by Herr A. Berberich. 
With regard to the book itself little need be said, 
except that the high standard of former years has 
been maintained. The 600 pages of references, with 
their brief and concise abstracts, cover the domain of 
astronomical literature for the past year, and a very 
complete name index concludes the volume. It may 
be incidentally remarked that the total solar eclipse 
of August, 1905, is responsible for no less than ninety- 
five references, which help somewhat to increase the 
bulls of the present volume. 
WOMMO3 i) VOL. 75) 
Zoologischer Jahresbericht fiir 1905. Herausgegeben 
von der Zoologischen Station zu Neapel. Redigirt 
von Prof. Paul Mayer. (Berlin: R. Friedlander 
und Sohn, 1906.) Price 24 marks. 
THE always welcome ‘* Naples Jahresbericht ” appears, 
as usual, well up to time, and its familiar features 
remain unchanged. Purely taxonomic papers are not 
included in the programme, but this limitation has 
been generously interpreted by some of the recorders. 
Where we have been able to test the lists we have 
found them full and accurate, and many of the 
summaries are models of terseness and clearness. If 
we look at the first section we are at once struck with 
the rapidly increasing number of important researches 
on the Protozoa; if we look at the last section we are 
similarly impressed with the number of papers deal- 
ing with Mendelian phenomena. The indefatigable 
editor, Dr. Paul Mayer, is responsible for the reports 
on Protozoa, Bryozoa, Brachiopoda, on part of the - 
Arthropoda, and on general biology—truly a heavy 
piece of work for a man who does so much else. To 
him and to his collaborateurs we offer in the name of 
zoologists our hearty thanks. 
LETTERS TO THE EDITOR. 
[The Editor does not hold himself responsible for opinions 
expressed by his correspondents. Neither can he undertake 
to return, or to correspond with the writers of, rejected 
manuscripts intended for this or any other part of NATURE. 
No notice is taken of anonymous communications.] 
Absorption of the Radio-active Emanations by 
Charcoal. 
Pror. RuTHEeRFORD in his interesting letter in Nature 
of October 25 (vol. Ixxiv., p. 634) on the ‘‘ Absorption of 
the Radio-active Emanations by Charcoal ’’ has no doubt 
quite unintentionally mistaken the general results of my 
experiments, and therefore I feel that some slight addition 
ought to be made to his communication. 
In the first paragraph of his letter Prof. Rutherford 
says that ‘‘ the interesting property of certain kinds of 
charcoal, notably that of the cocoa-nut, of rapidly absorb- 
ing gases, except the inert gases belonging to the argon 
family, is now well known since the recent experiments 
of Sir James Dewar.”’ 
Now, the statement made in the part of the paragraph 
I have italicised is not accurate. In my papers entitled 
“The Absorption and Thermal Evolution of Gases 
Occluded in Charcoal’’ (Proc. Roy. Soc., 1904), ‘* The 
Separation of the more Volatile Gases from Air without 
Liquefaction ’’ (Proc. Roy. Soc., 1904), ‘* Nouvelles 
Recherches sur la Liquefaction de 1’Helium ”’’ (Comptes 
vyendus, 1904), and ‘*‘ New Low Temperature Phenomena ”’ 
(Proc. Roy. Inst., 1905), I have shown that all the inert 
gases without exception can be condensed in charcoal as 
effectively as ordinary gases provided corresponding con- 
ditions of temperature, pressure, and concentration are 
maintained. 
In speaking of the ‘‘ many avenues for future inquiry ”’ 
opened up by the charcoal method of separating gases, I 
said (Proc. Rov. Soc., p. 130, 1904):—‘‘ The method I 
have described will be equally applicable to the treatment 
of the gaseous products from minerals containing helium, 
hydrogen, &c., and also to the radium products of the same 
kind. It seems even probable that the separation of the 
less volatile constituents in the air may be improved by a 
slight modification in the mode of working.’’ As a matter 
of fact, at the time of these communications to the Royal 
Society in 1904, I had made a few experiments on the 
condensation of the radium emanation by charcoal in vacua, 
and also on the separation of krypton and xenon; but 
during the last two years my health has been so indifferent 
that many lines of investigation have had to be abandoned. 
In my Royal Institution lecture of June 6, 1905, I ex- 
ce 
