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_Janvary 20, 1923] 
‘NATURE 
99 

as the underground arrangements differ so wide 
from what they do in America. Perhaps the most 
important point is the reference to skip hoisting, 
which has been introduced at several important shaft 
mines since 1918, the skips carrying loads of between 
to and 12 tons. At one of these mines a trial record 
of 1000 tons was hoisted in an hour, but all appeared 
to be capable of hoisting 7000 to 8000 tons daily. 
It must, however, be remembered that Illinois 
— are shallow, the average depth being only 
225 ft. 
The fourth chapter deals with details of methods 
of haulage, both on main lines and by gathering 
locomotives, which travel between the working face 
and the “ partings ’”’ on the main lines; where loco- 
motives are used for gathering, the length of secondary 
haulage ranges from 800 to 2000 ft. The operations 
are given in much detail and illustrated by tables of 
running times. It is shown, for example, that in a 
large colliery, where the average distance hauled on 
the main track is 4562 ft., a 15-ton locomotive hauls 
on the average 1035 ton-miles of coal per day and 
travels 24 miles. Gathering locomotives necessarily 
do very much less work than a main-line locomotive, 
the ton-mileage of the former being approximately 
ysth of that of the latter. This chapter further 
contains much useful information upon the construc- 
_tion of mine cars, and directs attention to the efforts 
that have been made to standardise car gy, and 
construction. It is interesting to note that an Illinois + 
mine requires about one car for every four tons of 
coal hoisted per day ; in comparing this with British 
figures, the larger size of the American car and the 
shorter length of the main roadways must be taken 
into account. The construction of the colliery track 
paratively little interest to engineers in this Sonntry, ) 
y 
both on main lines and also for secondary haulage is 
given in some detail. 
Underground haulage costs are carefully dissected 
in the fifth chapter. There is some difficulty in com- 
paring these costs with costs in this country, because 
in America costs of hoisting appear frequently to be 
included with those of haulage, under one head of 
transportation. It should also be noted in studying 
this chapter that the items of interest on plant and 
depreciation are not included. There is thus no real 
comparison possible between the cost of locomotive 
haulage and that of animal haulage, which in America 
always means mule haulage. The last chapter deals 
with accidents, and the importance of the subject is 
clear from the opening statement that ‘‘ For the past 
ten years haulage fatalities have been second in im- 
portance only to those from falls.’’ A dissection of 
the fatalities shows that the greatest number by far 
is due to men being caught and run over by cars or 
locomotives ; it is interesting to note that in 1920 
thirty-five deaths were due directly to the employ- 
ment of electricity and four to animals, a proportion 
of approximately nearly 9 to 1, whereas it has been 
shown that in 1921 there was more than ten times as 
much coal moved by locomotives, the vast majority 
of which are electric, as was moved by animals, so 
that, contrary to what might have been expected, 
the danger to life attending the use of the two methods 
may be said to be about equal. The section concludes 
with recommendations for the prevention of accidents 
>and a series of safety rules for underground haulage. 
It will be fairly obvious from the above summary 
that this bulletin is one of very real value to the 
mining community, and deserves the most careful 
study and attention from coal-mining engineers in 
this country. 
Science Teachers in Conference. 
ScIENCE MasTERs’ ASSOCIATION. 
N FARLY 350 members of the Science Masters’ 
Association assembled for their annual general 
meeting at Cambridge on Tuesday, January 2, when, 
by the kindness of the University authorities, they 
took up residence in Trinity and St. John’s Colleges. 
In the evening the members assembled in the Large 
Examination Hall, where the general meeting and 
presidential address opened a crowded programme 
of scientific lectures and demonstrations. Respond- 
ing to a general desire that the president should 
address the Association on some aspect of that 
branch of science which is so closely identified with 
his name, Sir Ernest Rutherford delivered an address 
on “ A Decade in the History of the Electron.”’ He 
reminded his audience of the characteristic and 
peculiar behaviour of the alpha particle and the 
evolution of our present ideas of atomic structure 
arising from the work of such investigators as Bohr, 
Laue, Moseley, and others. After referring to the 
essential features of radioactive disintegration, he 
to the consideration of the effect of the bom- 
ment of atoms with swiftly moving alpha 
particles and concluded by outlining some more 
recent work in which he had been engaged: this 
aimed at throwing “eg on the mechanism by which 
electrons are captured, and released, by such particles. 
A vote of thanks was proposed by Prof. Smithells, 
oo aebaegye: of the Association, and seconded by 
ir Richard Gregory, and the meeting then passed 
to the election of officers for the ensuing year. 
The following two days were largely absorbed by 
lectures, demonstrations in the various University 
laboratories, and visits to the University observatory, 
NO. 2777, VOL, 111] 
farm, and colleges; and if the parties visiting the 
colleges under the guidance of Sir Arthur Shipley, 
Dr. Rouse Ball, and others, were small, it must be 
attributed to the concentration of the scientific 
programme arranged, rather than to a lack of ap- 
preciation of the kindness of these gentlemen. 
In addition to the presidential address, four 
lectures were delivered to the Association as a whole. 
On Wednesday morning, January 3, Prof. Seward, 
the Master of Downing College, lectured on “ A 
Summer in Greenland,’’ in the course of which he 
described his experiences during the summer of 
1921 when on a tour of the coastal fringe of Green- 
land for the purposes of studying some of the botanical 
and geological features. Lantern illustrations ac- 
companied his remarks on the evolution of icebergs, 
on dyke formations, on Eskimo life, and on the 
characteristic flora of the country. Prof. Seward, 
in addition to his description of topographical features, 
pointed out the remarkable sinkage in the land, and 
also the probable resemblance between Greenland 
to-day and England in the Ice Age. 
On Wednesday evening the Chemical Lecture 
Theatre was crowded to hear Sir William Pope on 
the subject of ‘Crystalline Liquids.” Prefacing 
his lecture by a short résumé of the properties associ- 
ated with crystalline structure in the solid form, 
Sir William Pope proceeded to demonstrate, by the 
aid of the lantern-microscope, the existence of such 
a fundamentally crystalline property as double 
refraction in certain substances in the liquid con- 
dition, e.g. p-azoxyphenetole,  theaaeet opnespes and 
esters of cholesterol. The facile manipulation of 
these substances and the beauty of the polarisation 
effects shown on the screen were much appreciated. 
