JULY, ab;-1914] 
NATURE 
521 
tions obtain which make a practical test more helpful. 
Nevertheless, the temperature is of great importance 
and many means are employed of lowering it, such 
as adding salts which absorb heat on volatilisation. 
The rapidity of detonation, the length of the flame, 
and the heat evolved, all influence the readiness with 
which explosives ignite gas or coal-dust; but in this 
connection knowledge and progress have been chiefly 
promoted by direct experiment at the various testing 
stations here and abroad. 
The filling material for shells has been the subject 
of much experiment and trial by the different coun- 
tries. Picric acid, under the various names of 
melinite, lyddite, shimose powder, etc., has been ex- 
tensively tried and found wanting. Ammonal, con- 
taining ammonium nitrate, with a large percentage 
of trinitrotoluol and finely divided aluminium, is a 
very safe and powerful explosive, and has _ been 
adopted as the charge for shells by the Austrian 
Government. It has the disadvantage of containing 
the hygroscopic ammonium nitrate as an ingredient, 
and must consequently be specially protected against 
moisture. At present, trinitrotoluol is the body which 
has commended itselt to most of the Governments as 
the best bursting charge for shells, torpedoes, and 
general military blasting work, and has just been 
adopted by our own Government. 
Experience in America, South Africa, and Australia 
has shown that the fruit-grower has a real friend 
in explosives, and it seems to me that, in this country 
also, we must wake up to this beneficent aspect of 
explosives and the means they offer of attaining 
results otherwise impossible. 
In the case of tree planting, it is not the mere 
comparison of the cost of the excavation of the hole 
in which to place the tree which has to be considered. 
When an explosive is employed, the soil is shaken up 
and fissured for. a comparatively wide area beyond 
the hole actually required for the tree. When, as 
often happens, there is a hard and impervious subsoil 
beyond reach of the spade, this is also opened and 
fissured, and experience has shown that trees planted 
in ground prepared by explosives make a much more 
vigorous and rapid growth than when planted in the 
ordinary way. Some trees have begun bearing after 
four years, while others similarly situated but spade 
planted did not yield fruit until six years: 
In the case ot existing orchards little can be done 
in the ordinary way to aerate or render the soil more 
pervious to the roots and moisture, but a_ small 
cartridge inserted at some depth below the tree, or a 
larger one exploded at a depth of 3 ft. or so below 
the surface and midway between trees planted about 
15 ft. apart, has a most beneficial effect in loosening 
the soil without injuring the trees. The roots have 
less resistance to overcome, the soil is aerated, the 
moisture retaining properties improved, and a new 
lease of life is thus given to an old orchard; the trees 
become more vigorous and productive, and indeed are 
rejuvenated. 
UNIVERSITY AND EDUCATIONAL 
INTELLIGENCE. 
Lreeps.—The following appointments have been 
made :—Mr. Howard Priestman to be lecturer in tex- 
tile industries; Dr. A. M. Pryce to be demonstrator 
in bacteriology; Dr. H. E. Woodman to be research 
assistant in animal nutrition; Mr. H. A. Wyllie to be 
additional assistant lecturer and demonstrator in agri- 
culture. 
The second annual Yorkshire Summer School of 
WG) 2433, VOL: 93] 
| Geography will be held at Whitby on August 3-22. 
The work of organisation has again been undertaken 
by the University of Leeds, and the director of the 
school will be Prof. Kendall. The special subject this 
year will be the British Isles, treated in a general 
course, dealing with land forms and structure, meteoro- 
logy and economic geography. ‘There will be alter- 
native courses av the choice of each student on (1) 
agriculture, rocks and soils, and (2) oceanography, 
rivers and river development, and the evolution of 
transport. As in last year’s course, special attention 
will be paid to practical and field work. 
Lonpon.—The council of Bedford College has made 
the following appointments :—Assistant-lecturer in 
mathematics, Mr. C. Clemmow; demonstrators in 
physiology, Miss G. Hartwell and Miss N. Tweedy ; 
demonstrators in chemistry, Miss E. Field and Miss 
B. M. Paterson; demonstrator in geology, Miss I. 
Lowe. 
Dr. F. R. Miter, of the department of physiology, 
McGill University, Montreal, has been appointed pro- 
fessor of physiology in the Western University, Lon- 
don, Canada. 
Tue distribution of prizes at the Horticultural Col- 
lege, Swanley, Kent, will be held on July 23. The 
prizes will be presented by Lady Reid, and Sir George 
Reid, G.C.M.G., High Commissioner for Australia, 
will give an address. The chair will be taken at 
4 p.m. by Sir John Cockburn, K.C.M.G. 
Tue governors of the Imperial College of Science 
and Technology have appointed Dr. A. N. Whitehead, 
F.R.S., to the newly constituted chair of applied 
mathematics, and Dr. C. G. Cullis to the professorship 
of economic mineralogy. These changes form part of 
the general scheme of development of the Imperial 
; College ‘‘for the provision of the fullest equipment 
| for the most advanced training and research in various 
branches of science, especially in its application to 
industry.” 
THREE issues of the Undergraduate, the University 
of London magazine, published by the Students’ Repre- 
sentative Council, have been received. The first issue 
announced in December last that four numbers of the 
magazine would be published during the current ses- 
sion, and gave the last day for receiving contributions 
for the next issue as ‘‘1gth January, 1914.” Yet the 
second number bears the date May, 1914, and it says 
nothing of the number of issues during the session. 
The third issue is dated July, 1914. Sir Henry Miers 
writes in the December issue :—‘A magazine which 
will represent the University as a whole, and will give 
to all its members a medium of free expression upon 
the numerous and increasing matters of University 
interest will . . . satisfy a very real need.” We trust 
that the magazine will meet with the success to which 
the variety and interest of its contents entitle it. 
SOCIETIES AND ACADEMIES. 
LONDON. 
Royal Society, June 25.—Sir William Crookes, 
president, in the chair.—Sir W. Crookes: The 
spectrum of elementary silicon. The author has tried 
in vain for years to get pieces of fused silicon in an 
approximate degree of purity. Lately the Carborun- 
dum Co. at Niagara Falls sent him three samples 
giving an analysis of 99°56, 99'86, and 9998 per cent. 
