418 
THE GEOLOGIST. 
m^kc a catalogue of fossils, induces me to trouble you with a few lines on the 
subject of a catalogue wliieli [ iiavc nearly comjilctcd of my snuUl collection of 
minerals. 
I have arranged tlicni according to the orders into which Professor Mohs 
and llaidiuger divide minerals, as given in Allan's " Mineralogy." 
Order. 
I. Acid. 
IT. Salt. 
III. Ilaloidc. 
lY. Baryte. 
V. Kerate. 
VI. Zercne. 
VII. Malachite. 
VIII. Mica, 
IX. Steatite. 
X. Spar. 
Order. 
XI. 
XII. 
XIII. 
XIV. 
XV. 
XVI. 
XVII. 
XVIII. 
XIX. 
Gem. 
Ore. 
Metal. 
Pyrites. 
Glance. 
Blende. 
Sulphur. 
Resin. 
Coal. 
I have also divided them into the chemical classes of 
1st, Earthy and alkalino-earthy minerals, 
2nd, Acidiferous minerals, 
3rd, Metallic minerals, 
4tli, Combustible minerals, 
by adding a column for this purpose to the catalogue. 
I enclose a specimen sheet, and shall be glad if it meets with your approval. 
A few words on the subject of the principle upon which the above-mentioned 
" orders" were institued would greatly oblige me. 
I may mention that I intend to mark each specimen with the number of the 
order to which it belongs, and that the drawers containing the minerals in each 
order are also numbered. As the subject may not be wholly uninteresting to 
some others of your readers, perhaps at your leisure you will kindly favour us 
with a few more suggestions m a future number of your magazine.- — I remain. 
Sir, yours faithfully, A. B. M. W., Edinburgh. 
Order XI. 
Name of Specimen. 
No. 
Class. 
Locality. 
Gem. 
Rock Crystal 
1 
Earthy minerals 
Snowdon 
Caimgorum 
2 
ditto 
Arran 
Black Quartz 
3 
ditto 
Species Quartz 
Quartz Crystals 
i 
ditto 
Cheddar 
Chalcedony 
5 
ditto 
Lead-liills 
Flexible Sandstone 
6 
ditto 
Thibet 
Helioti-ope, or Blood-stone 
7 
Brun 
Species Opal 
Yellow Opal 
8 
ditto 
Mexico 
Order XII. 
Name of Specimen. 
No. 
Class. 
LocaUty. 
Ore. 
Specidar Ii'ou 
1 
Metallic minerals 
Elba 
Wood Tin 
2 
ditto 
Mexico 
Bro\vn Hematite 
3 
ditto 
Dover Cliffs 
We recommend to our correspondent a copy of W. Phillips' " Mineralogy" 
(any edition before the one by Brooke and Miller, especially the 4th), and 
to arrange her collection in the order that Phillips' adopted and uses in his book. 
It is the most practicable for general purposes. 
Elliott's Clinometers. — Sir, — Some time ago you promised to give an 
account of instruments in use by geologists. Will it be convenient, in the 
absence of this, to afford me some explanation of the two scales of the clino- 
meter made for geologists by Elliott Brothers, Strand. The principal gradu- 
ation on the brass arc is intelligible, being the quadrant divided into ninety 
degrees ; but the arc contains an inner line I | 1, 1 | i, 2, 3, &c. Query. 
