404 
NATURE 
[JUNE 10, 1915 


kinds (for the case of the circle), but they seem to |} 
miss the essential point, namely, that we are dealing | 
with the difference of two values of a linear function 
of a variable. As a contrast, let us suppose the depth 
of the sea increased an inch; this would mean the 
addition of many millions of tons of water. There 
are two principal reasons why results of this sort are 
truly paradoxical to most people, in the sense of being 
unaccountably surprising. Comparatively few people 
really appreciate the properties of the simplest mathe- 
matical formula; and, apart from this, it is a difficult 
thing to make a mental. scale of magnitude of any 
great extent. Thus observation and calculation con- 
vince us of the fact that if the earth were placed at 
the centre of the sun, the moon’s orbit relative to the 
earth would be inside the sun; but it is very difficult 
for people who are not astronomers to realise this in 
the same sense as they, realise that a pea will go 
into a thimble. 
In an address delivered before a joint meeting of 
the Franklin Institute and the Philadelphia Section 
of the American Institute of Electrical Engineers in 
January last, Mr. W..S. Murray, consulting engineer 
to the New York, New Haven, and Hartford Railway 
Company, reviewed the conditions affecting the success 
of main-line electrification. The experience of that 
line, which possesses 75 miles of four to twelve track 
electrified route are largely drawn upon. The system 
in us2 is the high potential single-phase with contact 
wire, and as it has enabled the coal bill of his line to 
be reduced so per cent-, Mr. Murray considers it 
superior to its rivals. He gives a long series of 
statistics of the amount of power generated at the 
central station, and the cost of operating the passenger 
and goods services and of maintaining the line and 
equipment. From these we gather that the total cost 
per train mile for power, engine-house expenses, loco- 
motive supplies and repairs, and train men is 73 cents, 
and per 1000-ton mile 47 cents. The address is repro- 
duced in the May number of the Journal of the 
Franklin Institute. 
Tue Bureau of Standards of the Department of 
Commerce at Washington has just issued a “circular " 
on “The Composition, Properties, and Testing of 
Printing Inks." This is a pamphlet of thirty-five 
pages, and deals concisely with various oils, pigments, 
driers, and formule for the making of printing inks. 
The relationship of the ink to the paper is also con- 
sidered, from the highly absorbent papers used for 
newspapers to the coated and wholly non-absorbent 
papers used for illustration work. In the former case 
the vehicle may be a non-drying oil, but where there 
is no absorption it is necessary to employ a quickly 
drying or hardening medium, though it must not dry 
on the formes or rollers. One of the most useful sec- 
tions of the pamphlet describes the “ink requirements 
of the Government printing office’ for web-press 
ink, job black ink, flat-bed black ink, and half-tone 
black ink, with the methods of making the practical 
tests. Actual printing tests under definite conditions 
are preferred for practically finding the qualities of 
various inks, because “if the article does all that is 
NO. 2380, VOL. 95] 

required of it, its composition is of minor importance.” 
But. analytical tests are valuable for ascertaining the 
causes of trouble in printing, the permanency of pig- 
ments, and so on, and, in the opinion of the director, 
there is room for a considerable extension of such 
work. The circular is a valuable addition to the 
technology of the subject. 
Ow1ne to the enormous quantity of oil which is’ 
now carried in bu!k annually across the oceans, con- 
siderable interest is attached to a paper on the evolu- 
tion of the oil tank-ship, read by Mr. H. Barringer 
at the Institution of Petroleum Technologists on May 
28. Although there is no written history of the earliest 
bulk oil-carrier, the Chinese Newchang junk, origin- 
ally built for the carriage of water in bulk, and after- 
wards used for oil, must be amongst the earliest 
examples of this class of vessel. The Chinese junk 
is provided with an expansion trunk, as in the modern 
steamer, the objects being to provide for the expan- 
sion of the oil caused by rise in temperature, and to 
keep the main hold always full, thus minimising the 
wash of oil due to the movements of the vessel. For 
some years, vessels carrying 6000 to 7000 tons were 
favoured by owners, but lately the tendency has been 
to build larger ships; in 1912 to 1914 the average was 
about gooo to 10,000 tons, although ten vessels each 
of 15,000 tons capacity were built. There are now 
about 434 bulk-oil, ocean-going steamers afloat, re- 
presenting a total gross tonnage of 1,637,000. One 
hundred and ninety-two of these vessels are fitted for 
burning liquid fuel. In the years 1910 to 1914 inclu- 
sive, 166 vessels were put into commission, having a 
total gross tonnage of 800,000, the output in these 
five years being equal to nearly half the tonnage now 
afloat. In addition to these steam vessels there are 
fifty-seven sailing ships representing 99,788 gross tons. 
Many of the recent ships are constructed on the Isher- 
wood principle of longitudinal framing. The oil- 
pumping arrangements are very complete. The capa- 
city of each of the four duplex pumps fitted to recent 
steamers is 300 tons per hour; these pumps are designed 
to deliver oil against a pressure of 250 Ib. per sq. in., 
and have enabled 15,200 tons of liquid fuel to be 
discharged in 313 hours through one 14-in. shore 
line. 
INFORMATION has been received at the Meteorological 
Office from the seismological observatory at Eskdale- 
muir of the record of a large earthquake which 
occurred on June 6, at about 9 p.m., G.M.T. The 
computed position of the epicentre of the disturbance 
is latitude 10° S., longitude 60° W.; that is, in Brazil. 
Messrs. WITHERBY AND Co., who are to publish 
“The Birds tof Australia,” by Mr. Gregory M. 
Mathews, announce that the subscription list will close 
on June 30, so that orders should be placed immedi- 
ately, as no new subscribers will be accepted in the 
British Islands after that date. The complete work is 
compiled from all published sources and from the 
author’s own observations, together with those of a 
large number of field-naturalists in all parts of 
Australia. The edition is strictly limited to 260 num- 
bered copies, more than two hundred of which have 
been already talxen up. 
