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[Marcu 25, 1897 
This photograph was selected for comparison with those of Mr. 
I’Anson because the rays are plainly shown, while the shadow 
of the mica sheet, which was between the coins and the photo- 
graphic plate, can also be plainly seen. It will be noticed that 
the rays are most numerous between the coins. 
FERNANDO SANFORD. 
Stanford University. Cal., February 19. 
[The photograph referred to by Mr. Sanford is similar to 
one which illustrated Mr. T’Anson’s letter (p. 270), the chief 
difference being that a greater number of rays are shown in the 
space separating the two coins. —Eb, NATURE.] 
Laboratory Use of Acetylene. 
IN your issue of September 3, 1896, appeared a short letter 
stating that acetylene was in use in our laboratory for blow- 
pipe work, and further stating that we hoped to introduce the 
gas on to the benches. From one or two inquiries received since 
then, it would seem that the fact of our now having succeeded 
in doing this will be of interest, as, indeed, it should be to any 
one possessing or contemplating the erection of a laboratory in 
the country where ordinary gas is costly or not obtainable. We 
use an ordinary Bunsen of special dimensions, the aperture of the 
jet being very small, and the tube (also of small diameter) is 
provided with a cap to protect the burner from dust when not in 
use. The generator is a modified form of one of those at present 
in the market, and gives between seven and eight inches water 
pressure. With six inches pressure a perfectly non-sooty flame 
of good size can be obtained, and a ‘‘ quarter Bunsen flame” 
under as little as three and a half inches. If turned lower than 
this, the flame becomes luminous, the draught becoming in- 
sufficient. The flame is steady, noiseless, and, unless turned too 
low, evinces no tendency to strike down. The consumption of 
gas averages one cubic foot per burner per hour. The flame 
possesses, of course, great heating power, one volume of acetylene 
being for practical purposes nearly twice as effective as one 
volume of ordinary gas. Thismeans an immense saving of time 
in all heating operations, and in many cases, such as small 
fusions and simple glass-working operations, we are able alto- 
gether to dispense with the blow-pipe ; the burner alone supply- 
ing quite sufficient heat. Our installation has only just come 
into use, but, so far, has given us no trouble. We have used 
an acetylene blow-pipe for nearly a year, and have had no 
difficulties. The cocks and general fittings should be thorougkly 
good ; any one who has not gone into the matter will be surprised 
to find what an indifferent article, as regards leakage, is the 
average gas-cock. It will be found that the cocks tend to work 
stiff, probably on account of the absorption of the acetylene by 
the lubricant, and it is much to be desired that the question of 
the most suitable lubricant should be investigated. 
The Laboratory, Felsted School, Essex. A. E. MuNBY. 
Immunity from Snake-bites. 
IN case any of your readers may be working on the subject 
suggested by Mr. Dawson Williams in Narure, March 4, 
page 415, that mosquitoes may be the carriers of pathogenic 
microbes, I send you the following. 
In a town in the interior of Asia Minor, where I resided some 
years, and where malarial fever was at all times very common, 
I frequently noticed that when the wind blew from the direction 
of swamps in the vicinity, bringing numbers of mosquitoes, 
there would be an increase in the number of men, both native 
and European, down with fever about a week later. Had the 
wind brought the malaria, or dust containing fever germs from 
the swamps, the increase in number of fever cases might have 
been expected within two or three days ; bufas generally a week 
elapsed, some less direct cause was to be sought, and I always 
thought the mosquitoes were the culprits. 
That mosquitoes do more than inject a specific toxin may be 
inferred from a fact I have noticed—that people who have been 
living in the interior of this country and have become inured to 
the bites of the insects from the swamps, on coming to this 
town, where sewerage and dirt of all descriptions abound, are 
painfully conscious of the attacks of mosquitoes here, and ace 
versa. 
Those who have suffered much from fever are generally im- 
mune from the usual pain of mosquito bites, and I have heard 
NO. 1430, VOL. 55)] 
natives say that they have suffered so much from fever that even 
the mosquitoes will not bite them. 
During the summer months, in certain localities in the interior, 
labourers are exposed to the bites and stings of tarantulas and 
scorpions. I have frequently seen men stung several times in 
the same season, and found that zzvaréably they suffered less from 
each successive sting or bite. J. Buiss. 
Smyrna, March 12. 
The Stereoscopic Studies of Clouds. 
SINCE 1894, I have been making stereoscopic studies of clouds. 
with wide separation of the cameras. 
Beyond the direct interest of the pictures, the method has a 
practical value. 
(1) In the measure of the distance of clouds by photogram- 
meters, it is usual to mark bya pin-prick the corresponding 
points of the two prints. Through the vagueness of cloud out- 
lines it is easy to err in doing this, but any error thus made is 
easily detected by the stereoscope. 
I have recently learnt that this method has been already 
suggested by Mr. M, J. Amsler-Laffon, of Schaffhausen, but I 
do not know whether it has been previously put to a practical 
test. 
(2) My photographs were taken by visible signal without 
electric connection, some of them with a base of fully five 
hundred yards, and the clear stereoscopic definition seems to 
show that in ordinary cases the expensive electric connection of 
the cameras may be dispensed with, without affecting the value 
of the plates for purposes of measurement. 
19 The Boltons, S.W. JoHN TENNANT. 
FAMOUS SCIENTIFIC WORKSHOPS. 
I.—LORD KELVIN’S LABORATORY IN THE UNIVERSITY 
OF GLASGOW. 
S Lord Kelvin stated nearly twelve years ago, in an 
address at the opening of the Physical and Chemical 
Laboratories at the University College of North Wales, 
the establishment of scientific laboratories at universities 
and colleges for the experimental training of students is 
a comparatively recent idea. Private laboratories, no 
doubt, existed at a very early period. The old alchemists 
had places, sometimes secret retreats, meanly appointed, 
like the den of Wayland Smith, sometimes, when the 
purse and protection of a powerful patron were at their 
command, more luxurious quarters, in which they carried 
on their search for the elixir of life, and the key to the 
transmutation of metals. 
Der in Gesellschaft von Adepten, 
Sich in die schwarze Kiiche schloss, 
Und, nach unendlichen Recepten, 
Das Widrige zusammengoss. 
When what was spurious and unscientific in the old 
alchemy had gradually sublimed away, when chemistry 
had grown up in its place, and the experimental study of 
natural philosophy had begun, the only laboratories 
(anatomical schools excepted), as a rule, were those in 
the houses of investigators, and to these admission was 
given by the masters only to their favourite disciples. 
There the work done was entirely that of research : such 
a thing as a course of laboratory exercises, carried on with 
a view to the passing of an examinational test of experi- 
mental knowledge and dexterity, was undreamed of. 
What a change has taken place! Now, no scheme of 
instruction in physics, chemistry, or biology is deemed 
complete which does not include an extensive course of 
practical work to be performed by the ordinary students ; 
and excellent and well-appointed laboratories are pro- 
vided at every institution which aims at giving university 
instruction in scientific’subjects. This is all as it should 
be, were it not that the examinational test is in too many 
cases made a great deal too much of. 
The Scottish Universities have often been criticised 
adversely, most frequently by men who knew little about 
