
Marcu 18, 1915 | 
NATURE 75 

to be tested on wheat plants grown in water culture. 
The harmful effect of the aldehyde, when added both 
to distilled water and to nutrient culture solutions, 
was so striking that an extensive series of experiments 
was undertaken in order to study the action of this 
compound on various plants and in various culture 
solutions, in soil in pots, and finally in the field. The 
plants used for the water culture experiments included 
wheat, maize, cow-peas, cabbage, and rice; for pot 
experiments trials were made with wheat, maize, and 
clover. In every case the depressing effect of the 
aldehyde was clearly shown. Thus in the case of 
wheat the addition of ten parts per million of salicylic 
aldehyde in distilled water reduced the growth by 
31 per cent. compared with the control; with fifty 
parts per million the plants were killed. The experi- 
ments suggest that calcium carbonate and calcium 
phosphate restrain the toxic action of the aldehyde to 
a slight extent, but the cultures under alkaline con- 
ditions indicate that its harmfulness cannot be attri- 
buted to any slight acidity it may possess. Field 
trials made with cow-peas, beans, and garden-peas 
showed that these crops were all reduced when grown 
in soil treated with the aldehyde. Finally, seventy- 
four samples of soils, talken from various parts of the 
United States, were examined for aldehyde com- 
pounds; seventeen of these gave positive results. 
Ten per cent. of the soils known to be productive and 
33 per cent. of unproductive soils contained aldehyde. 
The infertility of many of the soils is obviously due 
to causes other than the presence of toxic compounds, 
and especially of a particular toxic compound. 
AN interesting letter from Prof. John Perry appears 
in Engineering for March 12. The subject dealt with 
is cheap and rapid gun-making, and Prof. Perry 
describes some experiments carried out under his in- 
structions at Elswick, in which a cylinder of ordinary 
nickel steel, such as is used in guns, was constructed 
in such a manner that successive charges were ex- 
ploded in it, finally reaching the high figure of 52 tons 
per square inch, without apparent damage to the 
cylinder. The cylinder was cast solid, or nearly solid, 
under pressure, and turned and bored not quite to the 
finished sizes. The ends were closed, and means 
adopted for filling it with fluid under pressure. The 
temperature was maintained by rings of gas jets out- 
side (this prevents the yielding material from harden- 
ing too much). The internal pressure was raised 
rapidly to 17 tons per sq. in., and afterwards, during 
many hours, the pressure was increased gradually to 
4o tons. It had been intended to increase the pressure 
until the outside diameter became permanently (and 
not merely elastically) larger. Prof. Perry gives a 
full account of the theory in his letter, together with 
tables of values of the internal stresses, from which 
the thickness of gun tubes can be calculated. 
A PAPER was read by Sir Thomas Mason at the 
Institution of Civil Engineers on March 9g, giving 
particulars of the improvement of the River Clyde 
and the harbour of Glasgow from. 1873 to 1914. In 
1873 the river from Glasgow to Port Glasgow had an 
average depth of 15 to 18 ft. below low water, and 
NO. 2368, VOL. 95] 

25 to 28 ft. at high water. The largest vessels navi- 
gating the river had a draught of 22 ft. The total 
quayage of the harbour was 6410 yards in length, 
and the water-area was 76 acres. During the period 
considered, the Queen’s Dock, Prince’s Dock, Rothe- 
say Dock, and several graving docks have been com- 
pleted. Improvements on the river have had the effect 
of reducing the time of flow between Greenock and 
Glasgow ; low water has fallen at Glasgow about 2 ft., 
and is now 5 in. lower than at Greenock. In 1873 
springs rose ro ft. 6 in.; now the rise is 12 ft, 2 in. 
The tonnage of trading vessels has increased by 325 per 
cent., length by 56 per cent., breadth by 69 per cent., 
and draught by 48 per cent. Quayage has increased 
three times; tonnage of goods handled four and a half 
times; and revenue nearly three and a half times. 
The water-area of harbour and docks is now 535 
acres. 
OUR ASTRONOMICAL COLUMN, 
MELLISH’s COMET (1915a).—A recent number of the 
Comptes rendus (vol. clx., No. 9, p. 301) publishes 
observations of Mellish’s comet made at the Observa- 
tories of Lyons and Marseilles, The observations at 
the former were made by M. J. Guillaume between 
February 20 and 26, The comet is described as of 
the eleventh magnitude, with the aspect of a circular 
nebula about a half-minute of arc in diameter, with 
vague boundaries, and with a condensation or very 
small nucleus excentric towards the sun, The note 
by M. Coggia on the observations at Marseilles de- 
scribe the appearance of the comet as diffuse, irre- 
gular, without any brilliant part or condensation. Its 
magnitude is given as 11. The ephemeris given in 
this column last week extends up to March 24. 
Sun-spot AND MaGnetic Activity IN 1913.—Prof. 
A. Wolfer brings together in the Astronomische 
Mitteilungen (No. 105, p. 115) the very valuable statis- 
tics of the solar and magnetic acitivity for the year 
1913. The statement is based on the large number 
of observations made at numerous observatories, and 
affords a ready means of comparing the relative 
changes which occur from one year to another. The 
year I913 seems to have been a very quiescent one 
according to the value arrived at for the spot activity, 
and the diminution in activity from the year 1911 
will be seen from the following figures :— 
NOW ym MONA BHO Motes FOr 
This quiet state of spot activity is in close accord 
with the condition as deduced from the discussion 
of the mean areas and heliographic latitudes of sun- 
spots in the year 1913 at the Royal Observatory, 
Greenwich (Monthly Notices, R.A.S., vol. Ixxv., No. 1, 
oELO)s 
" The value for the daily variation of magnetic de- 
clination, on the other hand, has shown a pronounced 
indication of activity for the year 1913, showing that 
the minimum tools place in 1912, a year earlier than 
that of the sun-spot. 
Report oF Mounr WILSON SOLAR OBSERVATORY.— 
The annual report of the Mount Wilson Solar Ob- 
servatory gives the reader a good insight into the 
remarkable activity that has been, and is, in progress. 
Before proceeding to give somewhat in detail an 
account of the work in the various departments, the 
director, Prof. G. E. Hale, enumerates in the fifty- 
nine brief paragraphs the principal conclusions to 
which the work of the past year have led. These are, 
' of course, too numerous to give here, but many of 
