134 THE NORTHERN MICROSCOPIST. 
of the results it affords, and the amount of time it consumes, is 
stated to be in every way inferior to the new one. 
An inspection of the engraving (fig. 21) will show how this idea 
is worked out. On the top of a strong pillar, to which it is attached 
by a massive cradle-joint allowing of inclination in a vertical plane, 
is fixed the arm carrying the body, which latter is provided with 
rack adjustment, and a new and improved fine adjustment, render- 
ing unnecessary the usual often unsatisfactory loose nosepiece. 
The stage is so fixed with regard to the arm that the object when 
lying upon it is in a line with the centre of the cradle joint, so that 
upon inclining the body the object moves with it, and is presented 
at every possible vertical angle to a ray proceeding to it from a 
given direction. The stage is of a new and improved construction, 
being exceedingly thin—in fact the thinnest mechanical stage yet 
devised—and is capable of giving a complete rotation of the 
object. 
Beneath the stage swings the substage arm, concentric with the 
object, and carrying the usual screw centering and rack adjusting 
substage. 
Behind this substage arm is a strong bar, provided with a dove- 
tailed groove, into which the mirror bar slides. This is so pivoted 
to the substage arm, as to allow the latter to be swung aside, and 
the mirror used alone when requisite, without the trouble of taking 
the substage away altogether. This is a great advantage, as it 
permits the substage, and any apparatus it may be carrying, to be 
swung into or out of position ina moment with the mirror in the 
position here indicated. The stand has all the uses of the old forms 
of microscope, and can be employed in exactly the same way, but 
even then its peculiar motions round the object as a centre give it 
very great advantages in every class of investigation. But it is 
when the mirror occupies the position now to be described that 
the peculiar properties of the new stand are brought fully into play. 
The upright pillar, carrying the body and stage, is attached at 
its foot to a massive circular plate, carrying a graduated circle 
which rotates round a point exactly beneath the centre of the 
stage, and moving independently and concentrically with this is 
another smaller circle, having a dovetailed groove ploughed across 
it, into which the mirror bar can be slid when withdrawn from 
the substage arm. A spring catch attached to the dovetailed 
circle falls into a notch in the mirror bar when the centre of the 
mirror is exactly beneath the centre of the stage. This is the most 
useful position for the mirror, as a ray falling from a source of light 
upon it may be reflected upwards perpendicularly upon the object, 
when the body of the microscope is vertical, then without interfering 
again either with the mirror or lamp or interposing any accessory 
apparatus whatever, but simply by inclining the body the light falls 
