Wek E 
[Marcu 11, 1897 
notes make them most instructive publications. No. 7 
of the series contains papers of prime importance in the 
history of meteorological instruments, viz. the corre- 
spondence between Torricelli and Ricci on the measure- 
ment of atmospheric pressure, in which Torricelli 
announced the invention of the barometer (1644) ; and 
the paper “ Saggi di naturali esperienze fatte nell’ Acca- 
demia del Cimento,” in which the first continuous observa- 
tions with the thermometer and hygrometer are described. 
This paper appeared in 1666 and passed through eight 
Italian editions, and was translated into English (1684), 
Latin (1731), and French (1754). Prof. Hellmann gives 
a list of the most important works upon the invention of 
the barometer, thermometer, and hygrometer, and adds 
some interesting historical notes. 
No 8 of the “* Neudrucke,” entitled ‘‘ Meteorologische 
Karten,” contains facsimiles of the first wind-chart, 
isotherms, isobars, and synoptic weather-map, with an 
introduction in which the various charts are described. 
The wind-chart is Halley’s (1686); the isotherm map is 
Humboldt’s (1817) ; and the synoptic chart is Loomis’ 
(1846). Two maps of Le Verrier’s show the distribution 
of barometric pressures on September 7, 10, and 16, 
1863, as telegraphically communicated to the Paris Ob- 
servatory from different parts of Europe on those days ; 
and M. Renous’ map (1864) of mean atmospheric pres- 
sure over France is given as the first chart of mean 
isobars. 
The discovery of the secular variation of magnetic 
declination is told in Gellibrand’s “ Discourse mathema- 
tical on the variation of the magnetical needle,” which 
appeared in 1635, and is reproduced in facsimile as No. 9 
of Prof. Hellmann’s “‘ Neudrucke.” 
The three reprints are worthy additions to a very 
attractive and serviceable series. 
Colliery Surveying: a Primer designed for the Use of 
Students and Colliery Manager Aspirants. By T. 
A. O’Donahue. Pp. 163. (London: Macmillan and 
Co., Ltd., 1896.) 
WITH a view to reducing the number of colliery 
accidents, the law now requires that an accurate plan 
shall be kept of the workings of each mine. This has 
led to increased attention being devoted to the subject 
of mine surveying. Hitherto, it is true, mine surveying 
has not kept pace with the advances made in other 
branches of surveying. Great improvements have, 
nevertheless, been made during the last decade. Colliery 
managers are now submitted to a severe educational 
test before certificates are granted to them, and sur- 
veying classes are now held at most mining centres. 
For elementary students attending such classes, Mr. 
O’Donahue has written this concise little primer. 
Taking for granted that his readers have merely a 
knowledge of arithmetic, he has endeavoured to com- 
press into his pages a complete course of instruction in 
surface surveying, mine surveying and levelling, together 
with the requisite preliminary information regarding 
mechanical drawing, geometry, mensuration and the 
determination of inaccessible heights and distances. 
With so comprehensive a scheme, and with so small and 
inexpensive a book, the instructions are necessarily brief 
and, for the most part, unaccompanied by theoretical 
explanations. It is to be feared, therefore, that an 
elementary student working with this book without 
guidance might be led to learn by heart details without 
having grasped principles. Used under the supervision 
of a capable teacher, however, it should prove useful as 
an azde-mémoire to young students. The absence of an 
index is a serious drawback, whilst the superfluous section 
on the mensuration of solids could easily have been spared. 
Numerous typographical errors in the figures have 
escaped the author’s notice. Thus in the first example, 
NO, 14@a, VOU. 55) 
worked out on p. 34, there are three mistakes in one line, 
and in the next line the correct value of 15° is stated to 
be 1 in 3°74, whilst in the table of incline measure, on 
p. 142, it is 1 in 3°73. In that table itself there is often 
an uncertainty about the final figures ; for example, the 
correct inclines for 3°, 4° and 5° are I in 19°08, 14°30 and 
and 11°43 respectively, not I in 19'09, 14°29 and 11°42, as 
stated. On p. 140 the reduced level given is 50°3, but 
the measurement plotted in the drawing is 55 3. Again, 
the base line of the Trigonometrical Survey was measured 
in 1784, not 1874, as stated on p. 29. Trifling misprints 
of this kind, whilst perfectly obvious to the advanced 
student, are apt to prove stones of stumbling to the 
beginner. 
The British Mercantile Marine. By Edward Black- 
more. Pp. xix + 248. (London: Griffin and Co., Ltd., 
1897.) 
MEssrs. CHARLES GRIFFIN AND Co., Ltd., in their 
nautical series, have here a book not only serviceable to 
the men of the mercantile marine, but interesting and 
enlightening to those who wish to know the true state 
of our merchant service, which, to a great extent, and 
especially in smaller vessels, is manned by foreigners. 
The history commences with the infancy of the mer- 
cantile marine, giving the different laws passed, the state 
of trade, the different classes of vessels, and the modes of 
discipline at various times. Further on, the attention 
of the reader is drawn to the fact that our mercantile 
marine is suffering from the want of proper education, in 
that the examinations held for testing the efficiency of 
the masters and mates can practically only be passed by 
them through the medium of a “crammer,” who teaches 
them by rule of thumb, what is taught scientifically to the 
same class of men in other countries by their respective 
Governments. 
It is pointed out, further, that the apprentice, who is 
on board to learn his profession, at the commence- 
ment of his sea career performs only manual labour, 
seldom, if ever, having the opportunity of learning the 
art of navigation as opposed to seamanship; this holds 
good even for mates of smaller vessels. 
The book concludes with a postcript, entitled ‘* The 
serious decrease in the number of British seamen: a 
matter demanding the attention of the nation,” in which 
the author, in a few words, enumerates some of the 
points to which the decrease of British seamen is 
probably due. 
Bulletin of the Philosophical Society of Washington. 
Vol. xii. 1892-94. Pp. xxix + 567. (Washington : 
D. C. Jude and Detweiler, 1895.) 
THIS volume, though dated 1895, was only received a 
few days ago. A number of very interesting papers, 
some of which have been already referred to in the 
columns of NATURE, are contained in it, among them 
being the following :—‘‘The Mexican Meteorites,” by’ 
J. R. Eastman ; ‘“ Peculiarities in the Rainfall of Texas,” 
by A. W. Greely ; “The Origin of Igneous Rocks,” by 
J. P. Iddings ; “The Moon’s Face, a study of the 
origin of its features,’ by G. K. Gilbert ; “The Texan 
Monsoons,” by M. W. Harrington ; ‘‘ The Earliest Iso- 
clinics and Observations of Magnetic Force,” by L. A. 
Bauer ; ‘“‘ Mean Density of the Earth,” by E. D. Preston. 
Mr. Preston’s observations were made at Hawaii by 
two different methods, one depending upon triangu- 
lation and astronomical latitudes, and the other upon 
the diminution of gravity from the sea-level to the 
summit of a mountain, as revealed by a pendulum. The 
former method, carried out on Haleakala, gave for the 
mean density of the earth the value 5°57; the latter 
method, carried out on Mauna Kea, gave 5113 as the 
' density. The adopted mean is 5°35. 
