232 



Modern Microscopy 



Fifteen /* is a very good thickness for many objects ; 

 7 millimetres of material may be cut without readjust- 

 ment. 



The new ' rocker ' has engraved upon it the position at 

 which to set the sector for any required thickness. It must 

 be admitted that sections cut by either of these two instru- 

 ments are not cut in a plane, but in the arc of a circle, as 

 will readily be seen when the see- saw motion of the upper 

 lever is understood. This, however, is of little moment 

 when small objects only are concerned ; consequently, as 

 before mentioned, these microtomes are only suitable for 

 cutting small and soft objects embedded in paraffin. 



The same makers have introduced an instrument upon 

 similar mechanical principles that will cut larger surfaces 

 absolutely flat. These are admirable machines worthy of 

 attention, but still restricted to the paraffin method. 



As the object of these pages is to aid the microscopist in 

 his work, it is our duty to speak plainly, and to say that, to 

 the man who can only make room for one microtome, the 

 Cambridge * rocker ' should not be that one. But to the 

 enthusiast who can have two microtomes a 'rocker' will 

 prove a valuable possession for its special work. Lastly, 

 let no one imagine that the happy possessor of a ' rocker ' 

 has but to pull the knob to and fro and produce a beautiful 

 ribbon of sections. Success with a 'rocker' requires all 

 the skill wanted with the Thoma, Schanze, or Minot types, 



