124 
NATROL EE. 
[DECEMBER 10, 1903 
the wings. . . . In the resting position their identifi- 
cation is easy. In this attitude they can be dis- 
tinguished from all other blood-sucking Diptera . . . 
by the fact that the brownish wings lie closed flat 
over one another down the back, like the blades of a 
pair of scissors, while the proboscis projects hori- 
zontally in front of the head”? (p. 3) 
There is one peculiarity of Gl. morsitans that may 
be noted, viz. it does not lay eggs as do the majority 
of the Diptera, but extrudes a yellow-coloured larva 
nearly as large as the abdomen of the mother. 
Whether this process is the same in all species has yet 
to be determined. Of the seven species of tsetse de- 
scribed, one (GI. pallidipes) is new, and appears to be 
the East African representative of Gl. longipalpis. 
The work concludes with some valuable appendices of 
information from travellers, Government reports, the 
reports of Colonel Bruce and others. 
When the transmission of malaria by the mosquito 
was proved, the authorities of the British Museum 
rose to the occasion and published the magnificent 
monograph upon the Culicide by Mr. Theobald; 
again they have not disappointed us. In conclusion 
we would direct attention to the series of models in 
the entrance hall of the Natural History Museum of 
the trypanosome and tsetse fly, and of the malaria 
parasite and mosquito; they should be studied by all 
who may have the opportunity of increasing our know- 
ledge of these and other tropical diseases. 
Ike IPS Jel. 
METALLURGY OF STEEL. 
Hardening, Tempering, Annealing, and Forging of 
Steel. By Joseph V. Woodworth. Pp. 288. (West- 
minster: Constable and Co., Ltd.) Price ros. net. 
fa students who have ploughed through the weary 
sands of recent steel literature, Mr. Woodworth’s 
book will appear somewhat in the nature of an oasis 
in the desert. The author does not appear to be versed 
in the ‘“‘ites’’ of metallography, or fully to have 
giasped the allotropic theory of hardening, but, never- 
theless, he does thoroughly understand  tool-steel. 
Authors of papers on the restoration by heat treatment 
of faulty steel will hardly be prepared to acquiesce in a 
statement made by Mr. Woodworth on p. 18 of his 
book, namely, 
“Heating for forging is, in its way, quite as im- 
portant as heating for hardening; care and uniformity 
in the application of heat in the first instance is very 
essential. Should the steel be over-heated in this 
process, no amount of care afterwards will restore the 
steel to its former state or remedy the evil.’’ 
With the words above quoted everyone who has had 
an extensive practical experience of steel metallurgy 
will be more than inclined to agree. 
On p. 24 attention is directed to the fact that steel 
as delivered from the manufacturer is always more or 
less decarbonised on the surface. 
“* For this reason, do not select a piece of steel which 
will just ‘skin’ up, but take a piece large enough to 
require taking a good-sized cut before reaching the 
finished surface.”’ 
NO. 1780, VOL. 69] 
This is good advice, not only to mechanics, but also 
to scientific men making researches on the magnetic 
properties of steel. Mr. Woodworth, in concise and 
lucid terms, deals at considerable length with the 
machining, hardening, and tempering of nearly every 
class of steel tools, and the value of his letter-press is 
enhanced by a series of admirable illustrations (chiefly 
in perspective) of turning tools, taps, reamers, and an 
excellent set of milling cutters. 
A brief illustrated article on muffle furnaces (pp. 92— 
94) is well worth the attention of British artisans, as 
showing American practice, which is, on an average, 
undoubtedly superior to that obtaining in this country. 
That portion of Mr. Woodworth’s book dealing with 
the manufacture of dies and of drop forgings must 
necessarily be interesting to British manufacturers 
and workmen, because America was the birthplace of 
drop forgings, which were first manufactured by 
Colonel Colt, of revolver fame, in 1853. 
Another feature of the work now under review is the 
fairly complete and beautifully illustrated chapter on 
the emery-grinding of steel tools. Mr. Woodworth 
advocates as the highest type of forgings material 
which has been quenched in oil and subsequently 
tempered to remove contraction stresses. The views 
he expresses have already found favour with many 
experienced British steel metallurgists. 
On p. 162 Mr. Woodworth leaves, for the time being, 
a branch of steel metallurgy in which he is evidently 
a past master, and becomes controversial on the well- 
worn argument of steel v. wrought iron forgings. In 
deciding upon the superiority of steel, the author 
perhaps a little overdoes it, and his quotation from the 
report of the American Government tests on alter- 
nating stresses will hardly convince steel metallurgists 
who have closely studied this matter. 
The tests he quotes show that wrought iron is cap- 
able of enduring only 50,000 alternations. Steel, with 
0-25 per cent. of carbon, endures, before fracture, 
229,000 alternations, whilst steel with 0.45 per cent. 
of carbon sustains almost a million alternations. The 
author considers that these figures 
““ have given engineers an idea of the comparative en- 
durance of wrought iron and steel in such service as 
that to which crank-pins, shafting, &c., are subject.” 
Had Mr. Woodworth seen a verbatim report of the 
trial to decide the cause of the disaster on H.M.S. 
Bullfinch, which occupied several days at the 
King’s Bench in the summer of 1902, he would prob- 
ably have expressed a much modified opinion on the 
question at issue. Broadly speaking, the connecting 
rods of the Bullfinch were of the higher carbon limit 
just quoted; the rods of H.M.S. Snapper contained 
about the lower limit mentioned, namely, 0.25 per cent. 
of carbon. The rods of the Bullfinch snapped on her 
trial trip, causing lamentable loss of life. Those of 
the Snapper were taken out intact after the destroyer 
had run her trial trips and been four years in com- 
mission. 
An interesting portion of this book is the description 
of the Taylor-White process, which was the pioneer of 
those steels known as ‘‘speedy-cut,’? but quite 
naturally Mr. Woodworth does not specially direct 
