200 
MINUTES OF PEOOEEDINGS OF 
To correct a Shake. 
An instrument maker will re-burnish the glass. On service, the officer 
should remove the screws holding the glass, he should then screw out the 
glass and its case, either by the nicks on it or by pressing the handle of 
a turnscrew against the sides of the case. 
He should then take a turnscrew, and with its blunt side squeeze 
down tightly the brass rim binding the glass, or rather the three glasses, 
running the blunt edge of the turnscrew round and round this rim 
strongly until the glass shakes no more. 
He should then screw the glass and case into the instrument as tightly 
as he can, and bore new screw holes, and insert.the screws in them. 
Object Glass getting dim. 
In nine cases out of ten when this happens, it is really not the fault 
of the object glass, but of the eye-piece. 
Remedy. 
Take out the eye-piece and see if, in any position, it will give a clear 
image, if not, some of the internal glasses of the eye-piece may have slipped; 
shift them, and see if a clear image can thus be got; as it is impossible 
to do any harm, even to the adjustment, by fiddling with the eye-piece, 
this may freely be done. If wiping or changing the position of the eye¬ 
piece makes the telescope clear, bind the eye-piece in the best position. 
If the object-glass is dim, and it is not the fault of the eye-piece, screw 
out the object-glass; if there is dirt or moisture on the inside of the 
glass, wipe it off; if there is none, hold it up to the light; if the glass 
then looks clear, a mistake has been made, and the eye-piece is the real 
culprit; if, however, it is still very dim, moisture has got in between the 
three glasses, the brass rim must be raised up with the sharp end of a chisel, 
the glasses removed, cleaned, and the brass edge forced tightly down. 
All the above remarks apply also to the short telescope, save that the 
wires of this never require collimation. 
In conclusion, my advice to an officer, out of reach of an instrument 
maker, or of spare parts of instruments, would be this : 
Do anything you like with the eye-piece, even if you smash some 
of its glass, remove the broken parts and probably it will work without 
them (sometimes another glass as well as the broken one has to be 
removed). 
Never interfere with the wire pieces if possible. 
If there is a shake in the object glass, remove and correct it; but first 
be quite sure that the shake is not in your own fancy. 
A real shake will affect the observations; it will be also, when the 
forefinger is applied, not only felt, but heard to make a perceptible 
click. 
Do not remove the object glass for dimness, unless the instruments 
are unworkable. 
Out of 10 sets of instruments probably not more than one will suffer 
from any of these evils in three years. 
