432 



OPTICAL PROJECTION 



Fin. 243. -Vertical Pattern 

 Projection Microscope 



introduction of a long 

 girder bar extending 

 the whole length of the 

 instrument, and greatly 

 increasing the rigidity. 

 A centring sub -stage 

 has also been added. 



Sir David Salomons 

 has designed a modified 

 form of the instrument 

 which can be used 

 either horizontally or 

 vertically ; a large mir- 

 ror between the two 

 halves of the condenser 

 reflects the beam up- 

 wards, and a sort of 

 double prism above the 

 objective re-directs it 

 towards the screen. 

 The arrangement is 

 very handy for show- 

 ing pond life or other 

 objects which require 

 to be kept horizontal. 

 Both mirror and prisms 

 can be readily with- 

 drawn, and the instru- 

 ment then becomes an 

 ordinary girder pattern 

 projection microscope (fig. 243). 



Science lanterns. The large 

 growth of technical schools and poly- 

 technics has led to a demand for lanterns 

 for scientific demonstrations at moderate 

 prices, and several patterns of these are 

 now on the market. 



Professor H. Jackson, of King's Col- 

 lege, has designed such a lantern, which 

 is sold complete for 101. 10s. This lantern 



