MAT ORE 
517 
THURSDAY, SEPTEMBER 28, 1899. 
INCANDESCENT GAS LIGHTING. 
Léclairage  Incandescence. Par P. Truchot. Pp. 
x +255. (Paris: Georges Carré et C. Naud, 1899.) 
N looking back to the achievements of the past half- 
century, few domestic improvements will strike the 
observer more forcibly than the advances made in the 
development of light from coal gas. In the early fifties 
the metal flat flame and argand burners were looked upon 
as so satisfactory and so little likely to find a rival, that 
practically no efforts were made to improve them, and it 
was only in 1852 when the late Sir Edward Frankland first 
made his double chimney argand—afterwards known as 
the Bowditch burner—in which he led the air supply 
down between two glass cylinders surrounding the flame, 
and so utilised some of the heat which would otherwise 
have been wasted to heat the air supplied to the flames, 
and found as the result a distinct increase in illuminating 
power, that the idea arose that it was possible to obtain 
more than the two to three candles of light per cubic 
foot of gas consumed which the best burners then gave. 
Frankland’s burner marks the inception of the idea of 
regeneration as applied to an illuminating flame, an idea 
perfected by Siemens in 1879 and followed by a number 
of regenerative burners which doubled, and in some 
cases nearly trebled, the light obtainable from coal gas 
as compared with the ordinary burner. 
At the same period that the regenerative burner was 
struggling into prominence, Bourbouze, and later Lewis, 
devised a method of producing light from coal gas by 
burning it in a long bunsen burner, and making the 
flame impinge upon a mantle of fine platinum gauze, 
which heated to high incandescence gave more light 
than would have been emitted by the gas if burnt in an 
ordinary burner; and although this process never 
achieved much success owing to the fact that platinum 
soon got acted upon and lost its power of light emissivity, 
yet it was undoubtedly the forerunner of the incandescent 
mantle of to-day which has revolutionised our ideas as to 
artificial illumination, and yields ten times as much light 
for the same gas consumption as the ordinary No. 5 flat 
flame burner. 
So important has incandescent lighting become, and so 
abundant is the literature with regard to it, that the time 
had clearly arrived for it to be collected and welded into 
a handbook that should prove a guide and companion to 
all working in this branch of industry. This task has 
been undertaken by M. Truchot, who in “L’éclairage a 
incandescence par le gaz et les liquides gazéifiés” has 
given us a concise record of the history of incandescent 
lighting and a work of both theoretical and practical 
importance. 
In the twelve chapters of which the book consists, the 
author passes in review the properties and production of 
light, photometry, the proper distribution of light, the 
theories of Drossbach, St. John, Westphaal, Killing, 
Bunte and others who have attempted to explain the 
cause of the high incandescence of the metallic oxides 
forming the mantle skeleton, an excellent history of in- 
NO. 1561, VOL. 60] 
candescent lighting and a full account of the various 
minerals employed as a source of the rare earths and 
their treatment. Especially valuable will be found the 
description of the various methods of making the mantle 
and the chief points to be observed. 
The author then passes to the various forms of bunsen 
burner, and the results which can be obtained from them, 
but hardly gives sufficient credit to Bandsept’s inventions, 
which practically cover the ground upon which the chief 
advances in this direction have since been made. It 
would have been better also if a chapter had been de- 
voted to the theory of the bunsen burner, as it would 
have made the differences existing between the various 
forms of burner clearer. 
Very excellent in its way also is the chapter devoted to 
the lighting of the burners, and the effect which this has 
upon the life of the mantle. The author also goes fairly 
fully into incandescent mantle lamps for use with alcohol, 
petroleum and other easily gasifiable hydrocarbons. 
The book concludes with a review of the use of incand- 
escent lighting for railway carriages, lighthouses, photo- 
graphy, &c., and comparisons of incandescent light with 
other systems; whilst the list of French patents for 
mantles and burners forms a useful finish to the work. 
M. Truchot has done his work well, and his book 
should be in the hands of everybody interested in incand- 
escent mantle lighting. 
AN AMERICAN TEXT-BOOK OF GEOMETRY. 
New Plane and Solid Geometry. By W. W. Beman and 
D. E. Smith. Pp. x + 382. (Boston, U.S.A. : Ginn 
and Co., 1899.) 
HE Americans are an eminently practical people, and 
in seeking for the path of least resistance towards 
any desired end they are happily free from the shackles 
of inherited prejudice and irrational reverence for estab- 
lished tradition. This makes their mathematical text- 
books very instructive reading ; and although in some 
cases the desire for simplicity leads to a certain super- 
ficiality, this reproach cannot be fairly applied to their 
mathematical literature as a whole. Every reasonable 
person must admit that the simplest way of demon- 
strating a mathematical truth is the best one; and that 
energy wasted on the rudiments is so much loss of valu- 
able time which might have been spent with profit 
otherwise. 
The ‘‘ New Plane and Solid Geometry,” which is a 
revised edition of a work first published in 1895, illustrates 
very well the attitude of two experienced and competent 
American professors towards the problem of teaching 
elementary geometry. It is not to be expected that their 
work will meet with universal approval in all its details ; 
but it has many conspicuous merits which cannot fail to 
commend themselves, and deserves to be carefully studied 
by every teacher, whatever his personal views may be. 
The first thing to notice is the order and proportion 
which the authors have succeeded in maintaining. After 
a short, but very useful, introduction, there are eight 
Books dealing respectively with rectilineal figures ; 
equality of polygons; circles; ratio and proportion ; 
mensuration and regular polygons ; lines and planes in 
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