Beck Pathological Microscope. 
This microscope is of large size suited for research and advanced students’ work in 
bacteriological, medical and general work. It has several important features. The stage is 
of the built-in mechanical model where the entire top plate is moved both in the horizon- 
tal and vertical directions and can be cleared of all obstructions so that a culture plate 
or petri dish can be placed upon it and moved by means of the mechanical stage. The milled 
heads are under flush with the level of the top of the stage so that they do not prevent a large 
object lying flat upon the stage. 
The substage apparatus is interchanged by means of dovetailed (Akehurst) slides. The use of 
cylindrical fittings for changing the substage apparatus has great disadvantages, in that such fit- 
tings are difficult to change and generally necessitate the entire dislocation of the adjustments of the 
microscope. Now that dark ground illumination is practically a necessity in many branches of 
microscopy, it is frequently necessary to change rapidly from one form of illumination to 
another. With substage fittings of the cylindrical form this is troublesome, but the 
method adopted in the Pathological microscope enables this change to be made rapidly and 
with the minimum disturbance of the adjustments of the instrument. <A well fitted dove- 
tailed slide with an efficient clamping screw is a more accurate method of ensuring the correct 
alignment of substage apparatus. 
The Pathological microscope has been carefully examined and criticised by a number of 
experts in medical microscopy and many suggestions made by them have been included. It 
has been adopted at the London School of Hygiene and Tropical Medicine where the large 
equipment of microscopes consists of Beck Pathologicals. 
Base and pillar are of one heavy casting, the base being of the horseshoe pattern 
resting on three points, and having a spread of 5}in. by 7}in. The pillar has joint for inclination 
with stops for the vertical and horizontal positions. 
Stage is of the built-in mechanical model 
where the whole top plate travels. It has 
a movement of lin. in the vertical direction and 
1}in. in the horizontal. It is operated by two 
milled heads at the side of the instrument, 
which do not project above the level of the top 
of the stage, so that very large flat objects can 
be placed upon the stage without obstruction. The 
milled heads are in one form of the stage placed on 
r \ 
rs 
IAD 
i 7) the left hand side of the instrument so that the 
ANN SZ My . : 5 
=e ROT operator’s right hand is left free for drawing. They 
aes can however be fitted on the right hand side if this 
Topley top stage feature is not desired and if it is preferred to have 
them on the right. A sliding ledge can be fitted to the stage if desired. For objects mounted upon 
3in. x lin. slips, stage clips are provided, or the Topley top stage can be employed. The con- 
24 
