BRIDGMAN, ON INDEX TO SCALE. 
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other mixed objects, mounted dry or in any stiff medium, it 
is far better that every species should be represented by one 
or more slides, ignoring, as much as possible, everything else 
they may contain, and this plan affords by far the readiest 
and quickest means of accomplishing this end; and with 
reference to larger or even conspicuous objects, which, when 
placed upon the stage, are prevented from being seen by the 
setting of the object-glass, and are thus often troublesome to 
get into the field, it will be found an invaluable assistance. 
The same label may contain both the name and the dots of 
registry, and different coloured inks may be used for different 
objects, as well as labels be put upon both ends of the slide, 
and no reference having to be made elsewhere, the object 
can be placed at once upon the stage in its proper position. 
The label should be somewhat larger than the cover, and 
fixed upon the slide with its centre as near an inch from the 
centre of the cover as possible. This may readily be done 
by using another slide as a measure, holding it crosswise 
behind the one to be labelled, so that the two edges bisect 
the cover and the label equally. 
To prevent the labels becoming detached, the slides must 
be perfectly cleansed from grease and the paper thoroughly 
damped prior to using. A few hours' confinement in a tin 
box with damp sand will render the ready-gummed labels 
well conditioned for adhering. The only objection that can 
be urged against using the label is the possibility of its being 
lost, but this can only arise from defective manipulation. 
To complete it as a finder with a scale, the first step will 
be to provide a stop, d, fig. 2, on the right side of the stage 
plate. This should be so adjusted, that when the hole, b, in 
the papered slide is in the field, the movements of the stage 
shall be central, and the slide in the middle of the stage 
Fig. 3. 
plate. A very thin plate of brass, a, fig. 3, about an inch 
