268 
permanent mule track seemed to Prof. Bailey the best and 
only means of reducing the hardship of the ascent, and 
with true American ingenuity and enterprise he under- 
took the task of making a passable road up the sides of 
this barren mountain, over the remains of ancient lava 
streams and past huge slopes of volcanic sand, whose 
angle of ascent was oftentimes as much as 30. Indians 
and Spaniards alike ridiculed the attempt, but Prof. 
Bailey persevered with his design, in spite of fatigue, 
mountain sickness, sulphurous vapours and the yielding 
character of the ground, into which the feet of the mules 
would sink six inches at each step. How he finally suc- 
ceeded is modestly described in a chapter of great in- 
terest, to which we must refer for particulars. We can 
only record that at an altitude of 15,000 feet, approximately 
that of Mont Blanc, but in this latitude beneath the line 
of perpetual snow, the first observatory hut was set up, 
and, cheered by this success, it was resolved to attack 
the summit of the crater, and now eight feet above the 
highest point of the mountain a Robinson anemometer is 
successfully mounted, giving a continuous record of wind 
velocities in this elevated region. Other instruments 
from which records are obtained are a Richard self- 
registering hygrometer and thermograph, which register 
continually for ten days without interruption. Special 
thermometers and apparatus are mounted in a hut six 
feet square and seven feet high, on the very top of the 
mountain, a monument of well-directed vigour and in- 
domitable resolution on the part of the director. Wecan 
but offer our congratulation on the completion of a work 
of so much difficulty, and hope that the results will equal 
in interest the labour by which they have been secured. 
Whatever may be the final outcome of mountain meteor- 
ology, Prof. Pickering has definiteiy secured, through the 
untiring efforts of Prof. Bailey, a chain of meteorological 
stations from Mollendo on the Pacific to the headwaters 
of the Amazon. 
We have, unfortunately, but little space to do jus- 
tice to the work of M. Eginitis. A thick volume 
filled mainly with meteorological observations and their 
<liscussion is apt to prove somewhat wearisome reading, 
but the director has managed to introduce some features 
of interest. In fact, the publication of the volume itself, 
indicating as it does the renewed activity of an observ- 
atory which has been practically non-existent since the 
death of Dr. J. F. Julius Schmidt, cannot but be welcome, 
and we may venture to hope that the observatory from 
which so much valuable work has emanated in the past 
will again be found among the institutions that contri- 
bute to the progress of science. M. Eginitis gives in an 
interesting chapter the history of the observatory since 
its erection, a record which in spite of sundry interrup- 
tions should prove inspiriting, since it demonstrates that 
the energy and ability of successive directors have risen 
superior to the difficulties inseparable from small instru- 
ments and straitened means. The volume is divided into 
two parts ; in the first the climate of Athens is discussed, 
the treatise being enlivened by the introduction of many 
extracts from the old classical authors. In the second 
part are given the readings of the various instruments, 
by the discussion of which the climate is determined. 
W. E. P. 
NO. 1551, VOL. 60] 
NATO RE 
[JuLY 20, 1899 
MACHINES FOR THE LIQUEFACTION 
OF GASES. 
Liguid Air and the Liquefaction of Gases. By T. 
O’Conor Sloane, Ph.D. Pp. 365. (London: Sampson 
Low, Marston, and Co., Ltd., 1899.) 
HIS book may be regarded from three points of 
view: (1) as a popular account of recent work and 
experiments ; (2) as a scientific examination of the same ; 
and (3) as a historical summary and appreciation of in- 
vention in a special branch of science. As an instalment 
of popular science it has much interest. Readers who, 
guiltless of any exact science themselves, like to know 
what is going on in the modern scientific world, will find 
here a good deal that will help them to understand the 
significance of such steps in advance as are from time to 
time reported. Asan exact critique of the progress of 
invention it is not a success. On p. 300, for instance, Dr. 
Sloane says: “The origin of the methods used by 
Tripler, Hampson and Linde can be studied in the 
records of the Patent Offices.” Then referring to Mr. 
Tripler’s patent of 1893, he says the apparatus therein 
described “is based on self-intensification for the pro- 
duction of cold. The Joule-Thomson effect is not 
appealed to in it.” Shortly afterwards he says: “ Linde 
and Hampson have both invoked” the Joule-Thomson 
effect ‘as the principle on which their machines 
operate.” The teaching here, that, whereas the initial 
cooling in the Linde and Hampson machines is identical 
with the Joule-Thomson effect, it is in the Tripler 
machine produced in some other way, is entirely without 
justification and contrary both to good science and to 
common sense. The machines are all three based on the 
Joule-Thomson effect, and all three involve the use of 
self-intensification, while neither of these means is ap- 
plied in Mr. Tripler’s 1893 patent. More astonishing 
still, if Dr. Sloane is to be regarded as a scientific 
writer, are his approving references to this patent 
(its number, which he does not give, is 4210). This 
patent Dr. Sloane accepts as giving “a clear de- 
scription with drawings” of a self-intensive refrig- 
erator from which Mr. Tripler’s present apparatus is 
derived. The apparatus is not a refrigerator at all, for 
it contains a fatal fallacy, the omission of cooling coils 
after the pump, to remove the heat of compression ; 
while the circuit is so arranged that for liquefying air no 
such coils could be introduced. The apparatus there- 
fore, designed to produce cold, is a generator of heat. 
Secondly, even if it produced initial cooling, as expected, 
such cooling could never be intensified, since there is no 
self-intensive interchanger. An interchanger, to make 
the cooling effectively self-intensive, must have one end 
at the higher temperature, where the compressed air 
enters, the other end, where this air expands, at the 
extremely low temperature, and a continuous gradation 
of temperatures between them. In Mr. Tripler’s patent 
there is no interchanger in which such an arrangement 
is possible. Again, on p. 295, Dr. Sloane praises Mr. 
Tripler’s apparatus for its extreme simplicity, as using no 
refrigerant ; and after describing Dr. Linde’s more com- 
plex laboratory system, with its preliminary refrigeration 
by ice and salt, he says, on p. 320, that the Hampson 
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