May 26, 1870| 
NATURE 
73 
one of these proportions must cause a corresponding 
change in one or all of the above conditions. 
Thus, let there be a stream which in flood contains 5 per 
cent. by weight of solid matter, and let it be 8 ft. deep, 
discharging 50,000 cubic feet a second, with a mean velocity 
of 73 ft. a second—the breadth of this stream would be 
50,000 
8X7'5 
this stream of pure water would increase the discharge 
from 50,000 to 62,500 cubic feet a second, and the propor- 
tion of solid matter, instead of being 5 per cent., would be 
only 4 per cent. But, by the example before given, a 
depth approaching g ft. instead of 8 ft. would be the 
natural depth, so the bed would be lowered 1 ft., and the 
2 
breadth would only be increased ele 
= 8331. To add one-fourth to the discharge of 
of having to give an increase of one-fourth more, or 
8 j 
e = 208 ft., and still keep matters much as they are 
found in nature. 
So in bridging such a stream the whole additional 
length of viaduct would be only 92 ft., or 116 ft. would 
be saved by simply sinking the foundations 1 ft. more. 
But as water rolls rather than slides, and never flows in 
straight lines, the shape of the section of a stream can 
be changed at pleasure; so the depth may be increased 
without much danger by decreasing the breadth. Taking, 
then, the same stream which it was proposed to make 
833 +92 = 925 ft. broad by 9 ft. deep, suppose the mean 
depth be made 15 ft., this increase of depth would decrease 
the transporting power, while at the same time the velocity 
would also be increased ; and suppose it to be now Io ft. 
a second, instead of 7} ft., and with a depth of 15 ft. 
with such a velocity only 4 per cent. of solid matter 
could be held in suspension, and the waterway would be 
62,500 
15 X10 
one-half. That is, by adding 8 ft. to the general depth of: 
a stream where the river discharges 50,000 cubic feet a 
second in the main channel, and 12,500 cubic feet a second 
of inundation water, which is comparatively free of silt, 
the whole volume or 62,500 cubic feet could be passed 
through a bridge only half the breadth of the original 
stream, which was 833 ft. broad. So the whole question 
reduces itself now into one of cost. / 
The question is whether it be cheaper to sink the founda- 
tions an extra 8 or 10 ft., or to double the length of viaduct. 
By the use of the sand-pump foundations can now/e sunk 
through sand at a very moderate cost; so it is ‘believed 
that the extra sinking would not involve anything like the 
cost of the shallower foundations for the bridge built on 
the extended plan; thus the whole cost of the super- 
structure and extra girders could be saved—that is speak- 
ing approximately. In such a case the bridge built on this 
deep foundation principle could be built at nearly half the 
cost of the old plan; but to guard against accidents, and 
scooping out to excessive depths, it would appear that at 
least one-third may be saved by building bridges on this 
principle ; while the river, by having a deep channel under 
the bridge, could be kept in better ,control than by the 
present extended method, as it would not have such a 
tendency to desert its course, but would always keep to the 
deep channel. 
Several other examples may be brought forward to illus- 
trate the practical advantages that a better knowledge of 
the action of flowing water would be sure to confer on 
science and hydraulic engineering ; but it is hoped that 
the feregoing will assist in bringing the importance of the 
subject more prominently forward. When once the sub- 
ject is properly discussed I am convinced its importance 
will be manifested. 
= 4162 ft. broad instead of 925 ft., or less than 
T. LOGIN 
/were at once accepted as standards. 
SOCIETIES AND ACADEMIES 
LONDON 
Royal Society, May 19.—‘‘ Experiments on the Effects of 
Alcohol (Z¢iyZ Alcohol) on the Human Body.” By E. A. 
Parkes, M.D., F.R.S., Professor of Hygiene in the Army 
Medical School, and Count Cyprian Wollowicz, M.D., assistant- 
surgeon, Army Medical Staff. 
“On Deep-sea Thermometers.” By Staff-Commander John 
E. Davis, R.N. Communicated by Captain Richards, R.N., 
Hydrographer of the Admiralty. The results of thermometric 
observations at great depths in the ocean not being of a satis- 
factory nature, the attention of the hydrographer of the navy 
was directed to the defects in the construction of the 
Six’s. self-registering thermometers then in use, and also 
to the want of knowledge of the effects of compression on 
the bulb; and as it was known that a delicate thermometer 
was affected 7 vaczo, it was natural to suppose that an opposite 
effect would be had by placing them under pressure, and parti- 
cularly such as they would be subjected to at great depths. 
Several thermometers, of a superior construction, were made 
by different makers, and permission was granted to make expe- 
riments by pressure in a hydraulic press ; but much delay was 
caused by not being able to obtain a press suitable to the 
requirements, until Mr. Casella, the optician, had a testing- 
apparatus constructed at his own expense, and the expe- 
riments were commenced. Previous to the experiments 
being made, Dr. W. A. Miller, V.P.R.S., proposed, or 
rather revived, a mode of protecting the bulb from compression 
by encasing the full bulb in glass, the space between 
the case and the bulb being nearly filled with alcohol.* 
A wrought-iron bottle had been made to contain a thermo- 
meter, for the purpose of comparison with those subjected to com- 
pression ; but it failed, and finally burst under great compression ; 
it proved, however, of but little consequence, as those designed 
by Dr. Miller showed so little difference under pressure that they 
Two series of experiments 
were then most carefully made, at pressures equal to depths of 
250, 500, &c., to 2,500 fathoms, the results of which satisfacto- 
rily proved that the strongest made unprotected thermometers 
were liable to considerable error, and therefore that all previous 
observations made with such instruments were incorrect. Ex- 
periments were also made in the testing-apparatus with Sir 
Wm. Thomson’s enclosed thermometers, to ascertain the calo- 
rific effect produced by the sudden compression of water, in order 
to find what error, if any, was due to compression in the Miller 
pattern : an error was proved to exist, but small, amounting to 
no more than 1°°4 under a pressure of 3 tons to the square inch. 
The dredging cruise of the Porcupine afforded an opportunity 
of comparing the results of the experiments made in the hy- 
draulic testing apparatus, with actual observation in the ocean, 
and a most careful series of observations were obtained by Staff- 
Commander E. K. Calver at depths corresponding to the 
pressure applied in the testing apparatus ; the result was that, 
although there was a difference in the curves drawn from the 
two modes of observation, still the general effect was the same, 
and the means of the two were identical. From these experi- 
ments and observations a scale has been made by which obser- 
vations made by thermometers of similar construction to those 
with unprotected bulbs can be corrected and utilised, while it 
is proposed that by means of observations made with the Miller 
pattern in the positions and at the same depths at which obser- 
vations have been made with instruments not now procurable 
for actual experiment, to form a scale for correcting all obser- 
vations made with that particular type. In conclusion, it is 
suggested that to avoid error from the unsatisfactory working of 
the steel indices, which, from mechanical difficulties in their 
construction, cannot always be depended on, two instruments 
should be sent down for every observation ; and although their 
occasional disagreement of record may raise a doubt, a little 
experience will enable the observer to detect the faulty indicator, 
while their agreement will create confidence. 
London Mathematical Society, May 12.—Prof. Cayley, 
president, in the chair. The Hon. Sir J. Cockle, Chief Justice 
of Queensland, was proposed for election.—The President (Mr. 
* Vide Proceedings of the Royal Society, vol. xvii. No. 113, June 17, 1869. 
