502 NATURE 
[JuLy 18, 1912 
supervision is essential. Nevertheless, it is neces- 
sary that the engineer should be able to make 
accurate calculations, and in this work problems 
hitherto considered almost indeterminate have 
been successfully tackled. For example, one 
chapter—vi.—is devoted entirely to the deter- 
mination of the direct loads on columns, a matter 
of some difficulty, since the loading may be dis- 
tributed very ‘unequally over the supported con- 
‘inuous floors; complete mathematical analyses 
of beams under various conditions of loading and 
fixing are given in Appendix i. ‘ 
_ The resistance of beams to shear is investigated 
in chapter viii, and the considerations which 
guide a designer are fully discussed. Engineers 
and architects who specialise in this branch of con- 
structional work will find this book of great ser- 
vice, because the authors have not shirked the 
difficulties which face the designer of reinforced 
concrete structures, nor have they attempted to 
simplify calculations by neglecting important 
factors. ‘Ss ae Eee 
Handwoérterbuch der Naturwissenschaften. Her- 
ausgegeben von E, Korschelt, G. Linck, and 
others. Erste Lieferung (enthaltend Bogen 
I-10 des 1 Bandes)—Abbau-Algen. Pp. 160. 
(Jena: Gustav Fischer, T1912.) Price 2.50 
marks. 
Tuts encyclopedia, of which we now review 
the ‘first part, is ‘of a very comprehensive 
character, embracing botany, chemistry, geology, 
mineralogy, physics, physiology and zoology, and 
other natural sciences. More than 300 authors 
collaborate in the work; the list of these, given on 
the covers of this part, although mainly consist- 
ing of German names, includes also representative 
workers in special branches in England, the 
United States, Italy, Russia, and other countries. 
A special editor takes charge of each of the 
branches of science named above. 
_ The articles are arranged alphabetically, the 
following being a list of the principal articles in 
part i., with the authors’ names and number of 
pages covered. Abbildungslehre, 30, O. Lummer; 
Absorption, 20, K. Schaefer; Aether, 8, G. Red- 
delien; Aggregatzustédnde, 15, R. Mare and 
F. Noell; Aldehyde, 12, G. Reddelien; Algen, 40 
(uncompleted). This summary will serve to show 
the general scope and character of the work. The 
articles are authoritatively written by specialists 
and admirably illustrated; to each is appended a 
very useful bibliography. 
Numerous short biographical sketches of repre- 
sentative men of science are included ; for instance, 
in this number, E. Abbe, R. Abegg, M. Adenson, 
Agardh, Agassiz, Agricola, Sir G. Airy, Albertus 
Magnus, Aldrovandi, and d’Alembert. 
Such a book of reference should prove an 
extremely useful addition to the library of every 
scientific worker, not merely as regards the actual 
information imparted in the text, but as a ready 
reference to the more special literature of each 
subject. The work will be completed in about 
80 numbers, to be issued in the course of three to 
four years, forming in all ten volumes. 
NO. 2229, VOL. 89] 
GET TERS “LOM EE Se Dien OrRe 
[The Editor does not hold himself responsible for 
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the writers of, rejected manuscripts intended for 
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taken of anonymous communications. | 
Experiments with Kathode Rays. 
DurinG a research which is being carried out in 
conjunction with my colleague, Prof. Norman Collie, 
two experiments have been made the results of which 
are of some interest. Sir James Mackenzie Davidson 
was so kind as to furnish us with four deeply stained 
X-ray bulbs, which had been long in use, and had 
been rejected. These bulbs’ were broken up, the 
stained glass was placed in'a combustion-tube con- 
nected with a Tépler pump, and any adhering air was 
displaced by frequent washing-out with pure oxygen, 
admitted for the purpose. The tube was then heated 
to bright redness; and the gas collected was placed 
in communication with a small bulb of cooled char- 
coal, in order to condense out all gases except 
hydrogen, helium, and neon. The residual gas was 
run up into a capillary tube, in which its spectrum 
could be examined. The spectrum was mainly that 
of helium, but there was a trace of neon. — 
The second experiment consisted in exposing some 
calcium fluoride, prepared by precipitation, washing, 
and heating to bright redness, to the continued action 
of kathode rays. The surface turns purple, and sili- 
con fluoride, oxygen, and carbon monoxide are 
evolved. In order to maintain the vacuum best suited 
for kathode rays, a little oxygen was admitted from 
time to time. The gases evolved during some days’ 
bombardment were rejected, to make sure that no 
adhering gases were collected in the final experiment. 
These gases were pumped off four times; the fifth 
quantity of gas was examined. After absorption of 
condensable gases, the residue consisted of pure neon, 
without a trace of helium. 
From these experiments it would appear that not 
merely atoms of helium in rapid motion are capable 
of communicating sufficient energy to molecules and 
atoms on which they impinge to cause them to dis- 
integrate, but that electrons in motion, in the form 
of kathode rays, can be made to play a similar part. 
Wiiiam Ramsay. 
University College, London, July 16. 
Merlia normani and its Relation to Gertain Palzozoic 
Fossils. 
RecentLy I sent you a short communication (June 
6, p- 353) on Merlia normani, the siliceous sponge with 
a supplementary calcareous skeleton, stating that it 
was of a double nature, and consisted of a 
sponge living in symbiosis with a chlorophyll-contain- 
ing organism. Further, I stated that the name 
Merlia normani would have to be applied to the latter. 
I am glad to find, however, that this transfer of the 
name is not necessary, and that the sponge will con- 
tinue to be called Merlia normani. 
The discovery of the solution of the problem of 
Merlia is destined to prove of profound importance 
to paleontologists. For I now have convincing proofs 
—including, amongst others, the presence of siliceous 
spicules—that numerous Palzozoic fossils coming 
under the old-fashioned term ‘‘Monticulipora”’ are 
of essentially the same nature as Merlia, and that 
they are the supplementary calcareous skeletons 
of siliceous sponges. Merlia seems to be a solitary 
survivor of the Monticulipora type from Paleozoic 
times, though, of course, it may have acquired 
ee 
