I5-S TIIK HISTOIIV AND DEVELOPMENT OF THE MICEOSCOPE 

 "/''. /iiin-f'.i't'.i; tii-<> I.'in'ls of tube-length : (1) sun. optical and 



i,/>lii-iil (uli- li'injlh is measured from the posterior principal 

 point of the objective to the anterior jn-incipal point of the eye-piece. 

 Tli'- mechanical //"W<-/////// .should be measured from the top of 

 tin- mix- intn uhicli the t '\-i --piece fits, and upon which the bearings 



Fiii. 1-23. Old Ross stand (isfji. r.^atin^ fool l.rl,,\\ (\\,- pillar. From the cabinet 



"I tin' Koyal Microscopical Snrirty. 



pi' 1 '-' 1 resl to ill.- cud of the no.se-piece into which the 

 ulijcct i\ i- is scrru cd. 



iiatdy ditl'fivnt makers estimate nilM'-li-nyth differently 



Perenl points I'n.in \\hich to make their 'measurements. 



the matter lroadly. there are two estimates for tube- 



1 IIS(1 : these are the Kn-li>h and tho Continental. 



