354 
NATURE 
[August 13, 1885 
has had frequent opportunity of noting the phenomena of echoes 
by means of steam-whistles, guns, fireworks, &c., and has 
received distinct echoes from various surfaces, some of which 
were not very promising. The sails of vessels and an approach- 
ing tug-boat, referred to by Prof. Graham Bell, are additional 
sources of sound-reflection, but Mr. Lawton thinks that the 
echo in the case of the latter must have come from some other 
surface than the bows of the boat, which, unless very bluff or 
square, would have a tendency to reflect the sound at right 
angles. If it be true that in Atlantic voyages the sound of the 
steam-whistle is echoed back by the fog itself, then, Mr. Lawton 
thinks, the echo from an iceberg enveloped in the fog would be 
much sharper, more abrupt, and easily distinguished from that 
returned by the fog, which, from its varying density and elas- 
ticity, would more resemble a prolonged rumble. The import- 
ance of this subject, the number of lives and amount of property 
at stake would point to the importance of having every reason- 
able theory tested by ‘those most interested—viz. shipping 
companies, captains of steamers and sailing vessels crossing the 
Atlantic and those going to Australian and New Zealand by 
the Cape. In the present case this can be very easily done 
by means of the steam-whistle, ship’s bell, guns, &c., in broad 
daylight near an iceberg ; the circumstances, such as its size, 
bearing, and distance, the direction and force of the wind; and 
then it should be noted whether an echo is perceptible or not. 
Mr. Lawton appears to have gone to some trouble in bringing 
the subject to the notice of shipping companies concerned, and 
of describing the method of carrying out the few simple experi- 
ments needed to demonstrate the value of his theory, but ade- 
quate attention does not appear to have been given to his 
suggestions. We give them ina brief form here, in the hope 
that they may be fairly tested in the presence of an iceberg in 
daylight in such a manner as to enable shipmasters to estimate 
the practicability of the theory. He found that, during artillery 
practice near Hull, the opposite Lincolnshire coast, two miles 
off, returned echoes. There are no objects of greater height 
than a few cottages there, and it occurred to him the pheno- 
menon of echoes might be utilised by vessels in iceberg regions 
with more safety than the temperature test, especially if the 
wind and current be from the ship towards the berg. Most ice- 
bergs will present numerous reflecting surfaces at right angles 
to any passing ship, and it is anticipated that these surfaces 
would echo a short but full blast of the steam-whistle at a suffi- 
cient distance, say one or two miles, for the ship’s course to be 
slightly altered in case the berg was right ahead. If such a 
blast is blown in daylight in the presence of a berg for purposes 
of experiment, the distance and bearing of the berg, and the 
force and direction of the wind should be noted. If at the time 
a high sea or swell prevailed, the whistle should be blown when 
the ship is on the crest of the wave. As fog is a better con- 
ductor of sound than dry air, it is when an iceberg is enveloped 
in fog, as is often the case on the banks of Newfoundland, tbat 
Mr. Lawton’s theory, if true, would be of any value, as it could 
not only indicate the distance of the berg approximately, but 
also its bearing from the ship. 
THE Sadlers’ Company have established four studentships, 
each of the annual value of 30/., and tenable for two years, at 
the Finsbury Technical College of the City and Guilds of 
London Institute. The studentships will be competed for at 
the entrance examination, to be held at the college on October 1, 
and are open to pupils above fourteen years of age who are 
attending or who have attended any public elementary school in 
the United Kingdom. The Court of the Salters’ Company has 
agreed to raise their annual subscription to the Technical Institute 
from 525/. to 1000/. 
Dr. TRIMEN, director of the Royal Botanical Gardens of 
Ceylon, has just published a systematic catalogue of the flowering 
plants and ferns indigenous to or growing in Ceylon. The 
list gives the botanical, Singhalese, and Tamil names, and is a 
complete index to Thwaites’s ‘‘Enumeratio Plantarum Zeylaniz,” 
but it differs from the latter work in the sequence of the families 
or natural orders. In addition to the flowering plants and ferns, 
Dr. Trimen has added five natural orders—viz. Rhizocarpeze, 
Lycopodiacez, Isoetez, Selaginellaceze, and Characee. The 
catalogue includes 156 natural orders, 1071 genera, and 3249 
regular species, with 408 varieties, some of which may prove to 
be distinct species. The catalogue is issued as a number 
of the Yournal of the Ceylon Branch of the Royal Asiatic 
Society. 
THE weather in Southern Norway in June has been very 
remarkable, and we must go back to the year 1869 to find any- 
thing similar. The weather, early in the month, was very cold, 
the average being only 56°'5 F., while on the 11th the tempera- 
ture fell to 35°°8 F., a temperature which has not before been 
registered in Christiania in June, at all events not since 1867. 
Towards the end of the month the temperature in Christiania 
was abnormally high, reaching, on the 28th, 79°°3 F. in the 
shade. The rainfall was only half of the normal quantity. As 
well in May as June, the weather was below the average for the 
whole country. At Roraas the temperature fell on June 2 to 26°°6. 
The information received of the weather in the north of Norway 
to the middle of July shows that the weather had till then been 
very cold, the highest temperature being only 44°°6 to 46°°8 F. 
in the day and below freezing-point at night. It is popularly 
supposed that this is due to the enormous ice masses which 
have this summer descended from the Polar regions on the 
American side right into the Gulf Stream, which has thereby 
become greatly cooled, a circumstance immensely influencing 
the weather in Norway. Seal-hunters returning to Tromso from 
the White Sea and adjacent waters report that large masses of 
drift-ice are in motion towards the Norwegian shores ; but thereare 
as yet no reliable news from the Spitzbergen seas. On the other 
hand, we learn from captains who have returned from seal hunting 
on the east coast of Greenland and the sea north of Iceland that 
hardly any were caught, owing to the enormous ice-masses 
which are descending along the east coast of Greenland this 
summer, greatly in excess of previous years. It may be re- 
membered that last year the reverse was the case here. Liew” 
tenant Holm, who has been wintering on the east coast, reported 
that the sea was very free from ice even at the troublesome 
glacial promontory of Tuisortok, which has only once before 
been passed by Europeans, viz., Graah, It seems indeed that 
abnormal conditions prevail this summer throughout the Polar 
seas, and it will be of interest to learn what the state of the ice 
actually is north and north-east of Spitzbergen. 
A VERY interesting exhibit at the Inventions Exhibition is 
that of ‘(Brin Fréres” for the illustration of their method of 
extracting oxygen and nitrogen from atmospheric air by the 
agency of barium oxide and peroxide. A description of the 
process is given in a small pamphlet, but the English requires a 
little correctior. in places to be clearly understandable. The 
process of oxygen extraction by means of baryta is now very old, 
but has never yet been made real practical use of, the baryta 
becoming inactive after some time. This is no doubt due to the 
absorption of carbonic acid by the baryta from the air. In this 
process air freed from carbonic acid and water by caustic soda is 
passed over barium oxide heated in iron retorts to a temperature 
not exceeding 600° C. The temperature is regulated by a pyro- 
meter which regulates at the same time the supply of gas to the 
furnace. Under these conditions the oxygen of the air is 
absorbed by the baryta, peroxide of barium being formed. The 
nitrogen, which appears to be very pure, is collected separately 
for use in the production of ammonia. On heating the peroxide 
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