4 
WARD’S NATURAL SCIENCE BULLETIN. 
Besides the large stock of minerals mentioned 
from which we sell individual specimens, we pre- 
pare THREE SYSTEMATIC COLLECTIONS, with de- 
scriptive catalogues, as follows : 
The COLLEGE COLLECTION contains every re- 
quisite, even to a series of 50 crystal models, for 
a thorough illustration of the science of mineral- 
ogy. All the important species and their varie- 
ties are well represented in choice, handsome 
specimens, neatly labeled and mounted, and ac- 
companied by a special descriptive catalogue of 
39 pages. Price, securely packed and delivered 
at freight office in Rochester, $250. 
The ACADEMY COLLECTION, though numeri- 
cally not so rich, has really nothing of import- 
ance omitted. Thus, in the classification adopted, 
the elements are represented by 8 specimens ; the 
sulphides and allied compounds by 14; chlorides, 
etc., 6; oxides, 42; silicates, 64*; phosphates, etc., 
8; sulphates, 10; carbonates, 18; hydrocarbons/ 
10 — in all 180 specimens, well representing the 
relative importance of the different divisions. 
Each specimen in this, as in the other collections, 
is mounted on a separate black walnut block, to 
which is attached a printed label giving name, 
Dana’s species number, system of crystallization, 
chemical formula, and locality. In the case of 
single detached crystals, these are mounted on 
appropriate brass holders fixed in the block. 
Each specimen further bears a number by which 
it is described in the twenty-five pages of descrip- 
tive text accompanying the collection. This col- 
lection will be seen to answer the purpose ad- 
mirably for Normal Schools and Academies. 
Price, packed, $100. 
The COLLECTION FOR UNION SCHOOLS and 
Amateurs is in no wise to be confounded with 
some fragment-gatherings miscalled school cabi- 
■ nets, its specimens averaging very nearly, in size 
and beauty, those of the collections previously 
noted. The difference in price between it and 
the previous collection is due mainly to a decrease 
in number; while in all such specimens as are re- 
quired in elementary teaching, and with which 
every well-informed person is supposed to be 
acquainted, it is not lacking. 
These cabinets have all been planned with a 
direct and distinct regard to what was required in 
collections of the kind, and not from what mate- 
rial happened to be in stock, without thought as 
to what was needful. We think this will be ap- 
parent to those consulting our different cata- 
logues, where all details will be found. 
In addition to these, our standard collections 
with catalogues, we prepare smaller and cheaper 
collections, *as well as larger ones, of any desired 
extent. 
We offer an extra fine Cabinet of Minerals of our 
largest and choicest specimens for $4,000. 
PHYSICAL AND STRUCTURAL 
SERIES. 
In addition to the individual Minerals and the 
systematic collections above mentioned, we have 
prepared various special series of specimens com- 
piled to illustrate the physical and structural 
properties of Minerals : 
Lustre, Color, Diaphaneity, Fusibility, Specific 
Gravity, Hardness, State of Aggregation, Fracture, 
Structure, External Form. 
We also offer suites of CRYSTAL MODELS of 
various sizes, in solid glass, in plate glass (with 
axes and angles shown by colored threads), in 
wood (some revolving to show combinations), and 
in plaster (white or with colored faces). 
How Agates Are Cut. 
The variety of quartz known as Agate is a vari- 
egated chalcedony, with the color distributed in 
clouds, spots, or concentric layers. The variety 
called Moss Agate occurs in veins, while the 
banded agate is found in the form of geodes or 
balls, and occasionally there will be found in the 
side of these balls a sort of funnel through which 
was introduced the silicious matter forming the 
layers. 
Judging from the number of these agates to be 
seen one might be led into the error of supposing 
that they could be found almost anywhere along 
our shores, and as the prices at which they are 
sold are very low, it is evident that the cutting 
and polishing must be done in some country where 
labor is cheaper than here. However, the expla- 
nation is given when we are told that they are 
German Agates, for although for a number of 
years comparatively few agates suitable for cut- 
ting have been found on German soil, yet we may 
safely say that, at the present time, nine-tenths of 
all the commercial agates are cut and polished at 
the mills of Oberstein. The chief source of ag- 
ates now is South America, where, especially in 
Brazil, they occur in great numbers. They are 
shipped thence as ballast in vessels bound for 
Hamburg, and from this port are forwarded by 
rail to Oberstein, where they are sorted into lots, 
usually in the yard of some well known inn, and 
sold at auction. When purchased, they are sent 
to the agate mills,' where they are cut and pol- 
ished on wheels turned by water power, though 
of late years steam has been introduced in a few 
mills. 
Along the Idar River, between the towns of 
Idar and Oberstein, there were, in 1867, one hun- 
dred and fifty-three mills, working seven hundred 
and twenty-four stones. Each mill contains from 
three to five stones, set on a horizontal axle, one 
end running outside the workshop and commu- 
nicating with the water-wheel. The mill-stones 
are usually red sandstone, about five feet in diam- 
eter, and rotate in a vertical plane, the broad edge 
of the wheel being kept moist by a stream of wa- 
ter trickling down upon it from above. The 
choice agates are usually cut into shape with steel 
wheels and diamond powder. The common ones, 
however, are not sawn, but roughly dressed with 
hammer and chisel, the workmen acquiring, by 
long experience, great dexterity in applying their 
blows so as to obtain the desired fracture. 
The grinding is done on the broad edge of the 
wheel, which is furrowed with channels corre- 
sponding in shape with the form which it is de- 
sired to give the object in hand. The agate is 
usually attached to a small stick, and thus applied 
to the moving wheel. 
Each stone accommodates two men, but these 
men, instead of sitting at the wheel, are stretched 
in an almost horizontal position upon a wooden 
stool made to fit the body. The limbs are thus 
left free, the hands holding the agate to the wheel, 
while the feet are strongly pressed against blocks 
of wood fastened to the floor. After being 
ground, the agates are polished on cylinders of 
hard wood, or on lead or zinc discs, fed with a 
mixture of Tripoli and water. 
Many of the agates, beautiful as they are in 
nature, are artificially colored in the following- 
manner: having been well washed, they are 
placed in a sirup of honey and water, sometimes 
in olive oil ; after this, they are exposed for some 
time to moderate heat in a vessel embedded in hot 
ashes, care being taken that the liquid does not 
boil. When removed, they are washed, placed 
in sulphuric acid, and exposed to gentle heat. 
After they have taken color they are again 
washed, and it is often the practice finally to lay 
them in a bath of oil, which improves the lustre. 
Some layers of agate are quite porous, while oth- 
ers are dense and well-nigh impervious. When 
steeped in oil only the porous layers absorb the 
liquid, which, being deoxidized and blackened by 
the acid, makes the contrast between the layers 
more striking, thus enhancing greatly the beauty 
and value of the agate. Other colors are given 
agates by various processes; some, such as the 
reds, by simple exposure to heat; others by im- 
mersion in certain solutions, but these methods 
vary with the different lapidaries, and are more 
or less trade secrets. H. L. Preston. 
Likewise, Models in cut glass of the CELE- 
BRATED DIAMONDS of the world, containing ex- 
act reproductions of fifteen of these beautiful his- 
torical gems, from the handsome Pole Star — the 
original of which weighs 40 carats and belongs to 
the Princess Youssoupoff — to the valuable Kohi- 
noor of the British crown, and the immense dia- 
mond belonging to the Great Mogul, said to weigh 
297 carats. Also, models in glass of all the 
PRECIOUS STONES, faithfully colored and cut in 
appropiate forms, put up in sets of 40, 60 and 84; 
fac-similes of the celebrated Welcome Nugget, 
the Siberian Gold Nugget now in St. Peters- 
burg, and the immense Platinum Nugget be- 
longing to Count Demidoff; casts of interesting 
Meteorites; Goniometers, and all kinds of 
mineralogical apparatus. 
GEOLOGY. 
In this department we offer an extended series 
of material illustrating the composition and struc- 
ture of our globe, and of various phenomena 
which have attended its formation, or are still 
present upon its surface. Foremost is the divis- 
ion of 
LITHOLOGY. 
Here is first an immense storehouse of Rocks 
from all parts of the world, and to illustrate more 
definitely, though briefly, the cosmopolitan char- 
acter of our collections, we enumerate a few of 
the more important foreign localities from which 
we have specimens — many obtained during spe- 
cial and extended personal visits by Mr. Ward. 
Among IGNEOUS ROCKS, for example, we have 
varieties from the active volcanic regions of Li- 
pari, Sicily, and the country round Naples, as 
well as from the spent volcanic districts of Au- 
vergne, the Rhenish Provinces, Giant’s Causeway 
and New Zealand. 
METAMORPHiC ROCKS are contributed from 
localities in British Guiana, Trinidad, Mt. Blanc, 
China, Farther India away round to the Red Sea, 
and the Valley of the Nile; while to the quota 
of SEDIMENTARY ROCKS Mexico, the West Indies, 
East Indies, Australia, Arabia, Algeria, Egypt, 
Nubia and countless* European localities have 
contributed. These rocks are in specimens of 
uniform size, neatly trimmed, with fresh surfaces 
and well-marked characters. We have lately pre- 
pared with great care a number of 
GENERAL COLLECTIONS OF 
TYPICAL ROCKS. 
Three of these are arranged according to mineral 
composition, the importance of which, in the study 
of rocks, is daily becoming more evident as wit- 
nessed in the increase of literature pertaining to 
this subject. These three collections consist, re- 
spectively, of 50, 100 and 275 specimens, differing 
in scope to suit the wants of Union Schools, Acad- 
emies and Colleges. The first of these, the UNION 
SCHOOL COLLECTION, contains the most essential 
rocks, and is furnished packed for $20. The 
ACADEMY COLLECTION is more complete, and its 
price is $45. The COLLEGE COLLECTION is very 
full in varieties and localities, and contains many 
handsome, polished specimens illustrating the 
economical bearing of rock material. This col- 
lection will be furnished for $200. Two are 
arranged stratigraphically, and contain 100 and 
110, respectively, and are accompanied by chart 
of geological time; the former is a general STR ATI- 
GRAPHICAL collection from all parts of the world, 
price $50; the latter a characteristic series of the 
Rocks of the NEW YORK SYSTEM, the types of the 
Silurian and Devonian in America. Price $80. 
The collections are all neatly mounted on black 
walnut blocks with printed labels. 
