May 20, 1915] 
NATURE 
337 


Tue SocietA per il Progresso delle Scienze publishes 
in two small parts a summary (Spedizione Asiatica) 
of the remarkable work done by Dr. Filippo de 
Filippi in the Karakoram-Himalayas, but as this is 
even briefer than the accounts which have been already 
given in the Geographical Journal, we may await 
the volume, which will in due course appear, to supple- 
ment the one which described the exploring journeys 
in which he took part under the leadership of the 
Duke of the Abruzzi. Evidently Dr. de Filippi with 
his well-equipped expedition has succeeded, during an 
expedition lasting about sixteen months, in adding 
greatly to our knowledge of the physiography and 
petrology of a region in which Mont Blane would be 
an inconsiderable peak. 
IN interferometers it has been found convenient to 
introduce into the path of one: of the two interfering 
beams a plate of plane parallel glass of which the 
angle of inclination to the beam traversing it could 
be varied. By this means the optical length of the 
path could be increased by increasing the inclination of 
the plate to the path traversed. According to a note 
by Mr. L. H. Adams, of the U.S. Geophysics Labora- 
tory, published in the Journal of the Washington 
Academy of Sciences for April 19, a complete theory of 
the action of such a plate has not previously been 
available, and he supplies it. A number of important 
deductions may be made from the theory, one of 
which is the small effect of the index of refraction of 
the glass on the sensitiveness of the plate as a com- 
pensator. 
A RECENT paper by Mr. W. Calder on oil-well engin- 
eering, read before the Institution of Petroleum Tech- 
nologists on April 30, is well worthy of the attention 
of all interested in this highly specialised branch of 
engineering, and perhaps especially of young men who 
may be intending to devote themselves to this par- 
ticular department. In this country, where no prac- 
tical experience in oil-well technology can be obtained, 
there is perhaps too great a tendency to regard the 
subject almost exclusively from the geological view- 
point, and this paper comes opportunely to lay 
emphasis upon the engineering aspect of the work. 
It makes it very clear that, although for the location 
of the borehole the services of the geologist are indis- 
pensable, yet all the subsequent work depends for its 
success upon the engineering abilities of the man in 
charge. Well-drilling is purely a matter of mechanical 
engineering, and requires for its successful execution 
not only a thorough mechanical training, but an 
amount of resourcefulness and ingenuity that can 
never be acquired unless by men in whom the engin- 
eering instinct is innate. Mr. Calder’s paper brings 
the whole subject well up to date, and describes a 
number of the most modern drilling devices, which, 
though quite familiar to oil-well engineers, are by no 
means adequately dealt with in the general literature 
of the subject; it is therefore an exceedingly useful 
contribution to oil-well technology. 
Tue twin sciences of heating and ventilation have 
received little attention in their scientific aspects... In 
NOm2377; VOL. O5]| 
- a1 in., and a stroke of 1g in. 

a paper read before the Society of Engineers on May 
11, Mr. A. H. Barker dealt with a few of the difficul- 
ties of these subjects. He pcinted out that physio- 
logists are not even agreed upon what was a healthy 
temperature for human beings to live in. The heat- 
ing and ventilating engineer aims at producing com- 
fort, but is baffled by the fact that a man is com- 
fortable only when he thinks he is. Air which, judged 
by chemical analysis, is impure, may feel fresh and 
sweet, and vice versa. The only legitimate function 
of the engineer is to produce and control specified 
movements of air and other effects, while it should be 
the duty of the physiologist and hygienist to specify 
what are healthy and comfortable conditions. In con- 
nection with heating, the expression ‘‘ temperature of 
a room” is generally understood to mean the reading 
of a thermometer suspended in the room, but this 
reading does not necessarily indicate the temperature 
of the surrounding air, or form a trustworthy guide 
to the feelings of the occupants of the room. The air 
temperature, the radiant temperature, the quantity of 
convected heat and the quantity of radiant heat must 
all be determined, but first the relation between the 
thermometer reading, the air temperature, and the 
radiant temperature must be determined. The fresh- 
ness of air in a building depends on keeping the air 
temperature relatively low and the radiant tempera- 
ture high. The chemical composition of the air has, 
within wide limits, no effect on the human organism, 
whereas its temperature and humidity are very impor- 
tant. The paper described experiments made at Uni- 
versity College, London, and the apparatus used in 
connection with them, and discussed briefly some 
problems which it is sought to solve experimentally. 
A paPER on the distribution of heat in the cylinder 
of a gas engine was read before the Institution of 
Mechanical Engineers on May 14, by Prof. A. H. 
Gibson and Mr. W. J. Walker. The paper gives 
account of a series of tests made at University College, 
Dundee, in order to determine the jacket loss at 
different speeds. The engine, built by the National 
Gas Engine Co., Ltd., has a cylinder diameter of 
The water jacket is 
divided into two separate parts, one of which surrounds 
the exhaust-valve, and the other surrounds the breech- 
end and barrel of the cylinder. With the strongest 
mixture, and at full load, the percentage heat trans- 
mitted to the cylinder jacket is 1-10 times as great at 
150 revs. per min. as at 250 revs. per-min., while with 
the weakest mixture the ratio becomes 1-23. At 150 
revs. per min. the pericd of contact per cycle, of hot 
gases and cylinder walls, is 1-66 times as great as at 
250 revs. per min., and the rate of transmission of 
heat is evidently much greater at the highest speed. 
The indicator diagrams show that the maximum tem- 
perature attained in the cylinder is approximately 6 per 
cent. greater at 150 than at 250 revs. per min., so that 
the increased rate of transmission is obtained in spite 
of a lower gas temperature. The reason lies appar- 
ently in the fact that the greater turbulence of the 
working fluid at the higher speeds increases its effec- 
tive conductivity to an extent which more than counter- 
balances the other factors. 
