| astronomy, of December, 1903. 
as a transverse oscillation and explained dynamically. 
APRIL 21, 1904 | 
NATURE 
5o7 
ATMOSPHERIC TIDES. 
AN article on atmospheric tides, by Mr. W. Krebs, who 
is a frequent contributor to the scientific literature 
of Germany, appears in Das Weltall, a Berlin journal of 
The author points out that 
the astronomer Madler demonstrated in 1837 from the 
Berlin barometer observations the existence of an oscillation 
of air pressure in the course of a lunar day. The mean 
range exhibited a minimum pressure in the after- 
noon and a maximum in the forenoon of _ that 
period. This occurrence, which was found by Madler 
for the years 1820-1835, was confirmed by Prof. 
Bornstein with reference to the years 1884-1888, and was 
also shown to obtain at other German stations. But neither 
of these physicists ventured to affirm the existence of a tidal 
movement of the atmosphere in the oscillation which they 
had discovered. 
The hitherto purely statical conception of the oscilla- 
tions of air-pressure was an obstacle to such a theory. ‘This 
conception supposed a maximum of pressure to be simply 
the result of an elevation, and a minimum to be the result 
of a depression of the barometric column. According to 
this still prevalent idea, a maximum of pressure must be 
expected at the time of the upper culmination, and a mini- 
mum at the time of the lower culmination of the moon. 
The former was, however, found to occur at Berlin almost 
exactly five lunar hours after the upper culmination, and 
the latter about the same time after the lower culmination. 
For these reasons Midler thought it possible “‘ that there 
was a third way in which the celestial bodies acted upon 
each other, which was still unknown to us,’’ that is to say, 
other than by radiation and gravitation. 
But the atmospheric oscillation in the course of a lunar 
day, first discovered by Madler, appears to be nothing more 
than a wave caused by gravitation, when it is considered 
The 
greatest rarefaction of the air occurs about half-way after 
the lower culmination, corresponding to the greatest uprising 
movement of the medium. The greatest compression of the 
air occurs about half-way after the upper culmination, corre- 
sponding to the greatest downward movement of the 
medium. In both cases an attraction of the moon on the 
lower atmosphere of the earth is presupposed. The third 
kind of mutual action between the celestial bodies assumed 
by Madler accordingly reveals itself, in the case in question, 
as simply gravitation, when its effect is only considered 
from the standpoint of the wave theory. When applied to 
the solar day, the author considers that this view of the 
matter completes a missing link in the explanation of the 
double atmospheric oscillation according to Kelvin and 
Hann. 
ON LEAD POISONING AND WATER 
SUPPLIES. 
THE second volume on the above subject has recently 
been issued by the medical officer of the Local Govern- 
ment Board. The former volume contained information 
concerning Dr. Houston’s study of waters derived from 
moorland gathering grounds in Lancashire and Yorkshire ; 
the present volume gives details of an extensive series of 
laboratory experiments bearing on the general subject and 
conducted by Dr. Houston. They have been published in 
order to facilitate the interpretation of the results obtained 
when studying the solvent or erosive power of a water on 
lead pipes, with the view of counteracting these dangerous 
qualities. Particular attention is directed to observations 
on “‘ standards ’’ (p. 443) in this volume, where methods of 
measuring the solvent and erosive powers of a water upon 
lead are given enabling an opinion to be formed as to the 
degree of risk arising from the contact of such water with 
lead surfaces. 
The report is illustrated with drawings of the apparatus 
employed in the investigations, and photographs have been 
reproduced to show the actual amount of deposit remaining 
in the tubes in which the erosion of lead by water had been 
allowed to take place. 
From the nature of this report it will be understood that 
the substance of it consists of the tabulated results, together 
NO. 1799, VOL 69] 
with brief descriptions of the experimental methods adopted. 
The main conclusions arrived at were stated in the previous 
volume, but a general summary of all conclusions is also 
given in Section iv. of this volume. A reference to this 
summary will be found useful to those who are concerned 
with the consideration of dangers of lead poisoning arising 
from water supplies. +4 
The summary starts with an explanation of the meaning 
of the term ‘‘ erosion,’’ and proceeds to state that bright 
lead is rapidly eroded by rain and by snow water, as well 
as by distilled water; then follow the names of substances 
which do not influence the erosive power of water when 
introduced into it, as well as of substances which delay 
and inhibit the action. Moorland waters are next con- 
sidered in regard to their erosive property, and the con- 
ditions which increase, diminish, or prevent their erosion 
are stated. Then follow waters which do not fall under the 
above’ classification, together with remedial measures which 
may be adopted to avoid danger. A similar classification 
and consideration of waters as regards plumbo-solvency is 
then shortly entered into, and, finally, the conclusions arrived 
at from chemical and bacteriological experiments as to the 
cause of acidity in moorland water are given. The summary 
terminates with a selection of conclusions which have already 
appeared in the former volume. F. C. 
UNIVERSITY AND EDUCATIONAL 
INTELLIGENCE. 
Dr. H. H. Dixon has been elected professor of botany 
at Trinity College, Dublin, in succession to Dr. E. Percival 
Wright, who has resigned. 
Tue Princess of Wales opened the new buildings of the 
St. Paul’s Girls’ School at Broolk Green, London, W., on 
April 15. Accommodation is provided for a museum, 
chemical laboratory, and practical physics. 
Ar the request of the Board of Treasury the following 
gentlemen have consented to act as a committee to consider 
the allocation of the proposed increased grant to the uni- 
versity colleges giving education of a university standard 
in arts and science, viz. the Right Hon. R. B. Haldane, 
M.P. (chairman), Sir F. Mowatt, G.C.B., I1.5.0., Mr. C. A. 
Cripps, K.C., M.P., the Rev. Dr. Woods, late president of 
Trinity College, Oxford. Mr. Henry Higgs, of the 
Treasury, will act as secretary. 
AN annual commemoration day was inaugurated at the 
University of Glasgow on Tuesday. Sir William Ramsay 
gave a discourse on Joseph Black’s life and scientific work ; 
and after the oration several honorary degrees were con- 
ferred. At the commemoration banquet on Tuesday even- 
ing Mr. Choate, the United States Ambassador, remarked 
in the course of a speech that the universities had to do 
their best for the guidance of the councils of the nations 
to which they belonged. 
Tue council for the extension of higher education in 
North Staffordshire has issued its report for 1903. the 
objects of the council are to stimulate interest in higher 
education throughout the district, to assist in coordinating 
institutions and classes for higher and technical instruction, 
to aid existing institutions by the provision of supplementary 
and advanced courses of instruction, and to take steps for 
the establishment of a suitable institution in which to con- ~ 
duct a scheme of higher education for the benefit of the 
whole district. The report gives, among other information, 
reasons for the establishment as soon as possible of the pro- 
posed North Staffordshire University College, and urges the 
members of the council to join in the promotion of the 
scheme. 
Tue United States consul at Leipzig has, says Science, 
compiled a table of the number of students attending 
twenty-one German universities during the winter 1903-4. 
The total number of matriculated students at these universi- 
ties is 37,854, of whom 3093 are foreigners, the largest 
number ever recorded. The number of foreign students is 
equivalent to 8.2 per cent. of the total number. Of other 
students attending lectures in these universities there are 
7874 men and 1313 women, so that the total number, of 
students is 47,041. Noteworthy among other things in the 
