20 
Tomkins, on a Travelling Microscope. 
lization of the salts named would naturally follow from the 
fact of the metals themselves being less magnetic. 
Note. — My friend Mr. Thomas having having presented me with some 
crystallized specimens of sulphate of iron, cobalt, and nickel, of great 
novelty and beauty, I solicited him to write a short description of what 
they were intended to illustrate, and also his method of producing them, 
thinking it would be interesting to the Fellows of the Royal Microscopical 
Society. 
In his letter to me he says, “ If any one can offer a better explanation I 
shall be gratified. In trying to produce specimens there will be many 
failures, and it will require a considerable amount of practice and patience 
to produce similar results.” — W. Ladd, 11 and 12, Beak Street, W. 
On a Travelling Microscope. 
By J. Newton Tomkins, F.R.C.S., F.Z.S., F.R.M.S. 
(Read January 9th, 1867.) 
I am desirous of bringing before the notice of the Society a 
new microscope stand which possesses many points of merit, 
and is quite novel in some of its arrangements. The aim has 
been to combine lightness and extreme portability with 
steadiness and efficiency of work, while the essential element 
of cheapness has not been lost sight of. The whole apparatus 
is contained in a sling case, similar to that used for race- 
glasses, and weighs somewhat under two pounds ; it has 
been appropriately called the “ Travelling Microscope,” from 
its manifest capabilities. The compound body is firmly 
attached to the front leg of the tripod stand, the two other 
legs are supported on capstan-bar joints (to be tightened at 
pleasure should they work loose), which fold up when not in 
use. The tripod forms an exact equilateral triangle, with the 
view of ensuring the greatest possible steadiness, and the feet 
are shod with cork in order to diminish vibration, as well as to 
prevent the instrument from slipping on a smooth table. The 
tube, which allows of elongation to an extent of eight inches, 
slides in a jacket lined with cloth, and the coarse adjustment 
is gained by this sliding motion ; the fine adjustment is 
effected by means of a tangent screw of fifty threads to the 
inch, which is placed conveniently behind the body, and 
worked by a milled head acting on a spring contained in the 
upright which supports the body. This portion of the instru- 
ment works smoothly and satisfactorily. 
The stage is formed of a simple brass plate, with spring 
