50 NATURE 
[May 21, 1885 
thus proposed was not sufficiently startling, it was gravely 
suggested (p. 2) that the five orders of reptiles were 
“analogous” to similar subdivisions in birds and mam- 
mals ; the lizards as “climbers” representing the Z7sess- 
ores in the former and the /77maZes in the latter, serpents 
being “carnivorous” corresponding to Accipitres and 
Fer@, Emydosaurians (crocodiles) because they are 
“aquatic” to Amseres and Cefe, tortoises in virtue of 
being “large-footed” to Galline and Ungulata, and 
Amphisbenians for no particular reason to Gral/e and 
Glives. Jt is doubtful whether the authorities of the 
British Museum would not have done wisely by leaving 
this farrago of nonsense, one of the last echoes evoked by 
the once popular quinquennial system of Vigors and 
Swainson, in well-merited oblivion, and in not calling 
attention to it by suggesting a comparison between the 
work by Dr. Gray and that by Mr. Boulenger. However 
great may be the changes in zoological classification 
during the next forty years, the difference between the 
views now held and those that may prevail in the future 
will scarcely be so revolutionary as that which exists 
between the first and the second edition of the British 
Museum Catalogue of Reptiles. 
THE SILVER-LEAD DEPOSITS OF 
NEVADA 
The Stilver-Lead Deposits of Eureka, Nevada. By J.S. 
Curtis. 4to. 200 pp. (Washington, D.C., Govern- 
ment Printing Office, 1884.) 
aP HE remarkable mineral district which is dealt with in 
this memoir is situated in the eastern part of the State 
of Nevada, about the centre of the dreary region known 
as the Great Basin, between the Great Salt Lake of Utah 
and the Sierra Nevada range of California. The business 
centre of the town, or “mining camp,” of Eureka is about 
go miles south of the Palisades Station, on the Central 
Pacific Railway, with which it is united by a narrow- 
gauge branch railway. The principal mines situated 
about Ruby Hill, about 14 miles west of the town, extend 
for about a mile along the contact of a limestone, sup- 
posed to be of Cambrian age, with an underlying quartzite. 
The quartzite forms the axis of a steep anticlinal arch, 
which has been modified on one side by a great fracture 
known as the Ruby Hill fault, and between this and some 
secondary fractures, an enormous mass of crushed lime- 
stone is included, containing the mineral deposits, or ore 
bodies proper, which are essentially cave deposits, the 
hollows between the limestone fragments, which are of all 
sorts of shapes and sizes, being filled with products of the 
oxidation of galena, pyrites and mispickel, such as 
sulphate, carbonate, and arsenate of lead, and brown iron 
ore, in addition to the unaltered minerals in smaller 
quantities. The chief mineralogical find of these mines 
has, however, been of Wulfenite or molybdate of lead, 
which has been produced in considerable quantity, both 
in detached crystals of great beauty and interspersed 
through the mass of the other minerals. As a whole, the 
ores contain about 33 per cent. of lead, 30 ozs. of silver, 
and about 1? ozs. of gold per ton. These ore bodies are 
of every possible form and size, from small strings up to 
masses measuring upwards of Ioo feet in all directions ; 
but in spite of this great irregularity of form, they 
are generally connected with systems of fissures or 
channels, and it is by following these fissures that most 
of the great discoveries have been made. 
Although mines extend for nearly a mile along the hill, 
the most valuable portions of the deposit are included 
within a length of about 500 yards at the north-western 
end belonging to the Eureka and Richmond Mining 
Companies ; and, as the largest development of ore has 
been on or near the boundary dividing the two properties, 
disputes as to the ownership of different masses have been 
followed by litigation culminating in a law-suit which in 
some way recalls the famous Torbane Hill case of the 
Scotch courts; the principal mining and geological ex- 
perts of the United States, when called in as witnesses, 
being about equally divided in opinion as to whether the 
zone oi limestone containing the ore was a lode or not. 
In the first judgment the affirmative view prevailed, and 
was maintained on appeal, although the case appears to 
have been ultimately decided upon considerations of 
previous agreements as to boundary lines between the 
two companies rather than on technical definitions. The 
absurdity of attempting to apply precise definitions to 
such essentially irregular objects as mineral deposits 
has never been so well demonstrated as in this famous 
case. 
As regards the origin of the ores, the author considers 
them to have been deposited by hot springs constituting the 
final episode of a period of volcanic activity, evidence of 
which is found in the neighbourhood, though not in the im- 
mediate vicinity of the mines. A large number of assays 
of the limestone and quartzite rocks enclosing the de- 
posits have been made, proving them to contain silver of 
the value of from fourpence to twenty-two pence per 
ton, which, however, in the author’s opinion shows con- 
clusively that the materials for the ore could not have 
been derived from any of the sedimentary formations. 
The systematic assaying of the rock has been attempted 
to be utilised as a method of discovering ore bodies, as 
have also experiments upon variations in electrical 
activity, but as yet without practical results, although a 
curious coincidence has been observed in the indications 
given by the two methods. 
The yield of precious metals of the Ruby Hill mines 
between 1869 and the date of the author’s report, 1883, 
has been about 15,000,000/., the value in the proportion 
of about one-third of gold to two-thirds of silver, in 
addition to about 225,000 tons of lead. Both the smelting 
and desilverising of the ore are done on the spot, the 
latter being effected by the inverse Pattinson process of 
Luce and Rozan, in which the lead is crystallised by 
injecting steam, and the liquid lead is run off from the im- 
poverished crystals. This is perhaps the largest applica- 
tion that this process has yet received. 
The lower workings of the mines, although they have 
been extended to a depth of 1200 feet, have not as yet 
led to any discoveries comparable with those made be- 
tween 300 and 700 feet below the surface. The author, 
however, considers the chances of finding ore in depth to 
be favourable. 
Taken as a whole the volume is a very interesting one, 
and is well illustrated, although for practical purposes 
the scale of the plans and sections is rather small, and 
