CHAS. LENTZ & SONS 
Cbe Grana moael microscope 
DS AND DDS 
This microscope stand is an ideal instrument in the fullest sense of that word ; 
viz., perfect in design as far as the limitations of the human mind will permit, and 
perfect in construction as far as it is possible for human skill, to perfect anything. 
The stand is of the finest brass throughout, and is finished in the most appro- 
priate manner in every part. The base, while of the horseshoe type, is extra 
heavy and has the back claw prolonged so as to virtually form a tripod base which 
is entirely stable in any position of the microscope. The pillar, consisting of two 
massive columns, supports the stage and arm in a manner particularly adapted to 
secure solidity and at the same time add grace to the instrument. The stagfe is 
of unasually large size, measuring 126 mm. in diameter, and is either fitted with 
vulcanite plate in the DS, or with mechanical stage in the DDS stands. In either 
case the stage is revolving and with centering screws, whereby the geometrical 
center of the stage may be made to accurately coincide with the optical axis of the 
objective. The mechanical stage suj^plied with the DDS stand is the same as that 
described on page 25, except that it is larger, to conform to the larger stand, and 
has both the stop against which the object slide rests and the movable finger 
adjustable and provided with graduations for record purposes. The heads of the 
centering screws are also provided with graduations and index and with a series 
of lines recording the number of revolutions of the screw. These extra g;radtja- 
tions make this the only microscope made with revolving mechanical stage with 
which it is possible to accurately record the position of any given object in such a 
manner that it can be referred to again if the instrument shall have been used ad 
interim for other work. This is very important in projection work for class 
demonstration. 
The mechanical stage is readily interchangeable with the plain revolving 
stage, as both are made to standard gauges. To effect the change it is only neces- 
sary to loosen the centering screws and substitute one stage for the other. The 
purchase of both stages is recommended, as the plain stage will often be required 
where the mechanical stage would not be, and vice versa. 
The large body tube, especially constructed to permit a large cone of light to 
pass from the objective, as well as its complete adjustments, fits this stand for 
Photo-micrography. 
The fine adjustment is the improved triangular bar adjustment, in which the 
movement is by micrometer screw of such accuracy and delicacy that there is abso- 
lutely no lost or lateral motion possible. In order to give increased delicacy in 
manipulation the head of the micrometer screw is made extra large and has a con- 
cavity at the apex in which to rest the index finger for greater steadiness. The 
circumference is graduated to 100 parts, permitting measurement of the thickness 
of objects under observation. 
