INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 619 



pressure given by common elastic bands admirable, and they can be 

 renewed at a nominal cost. 



The two holes shown in both the tables are to take springs in 

 order to be able to use it in the usual way for old slides. I have 

 found it of great advantage to make the support for the hand (not 

 shown in the figures) slide back so as to be able to take in exception- 

 ally large or deep cells. 



Large Micro-photographs.* — Dr. S. Th. Stern says that to obtain 

 a micro-photograph on a large scale the screen of the camera has to be 

 placed at too great a distance from the objective for the operator to be 

 able to adjust the focus without complicated machinery for connecting 

 the fine adjustment with the camera which is uncertain in action, 

 troublesome to work, and of considerable cost. He dispenses with the 

 machinery by simj^ly placing a mirror behind the ground-glass screen. 

 The image thrown upon the screen is reflected in this mirror, and 

 may be viewed through an opera-glass by the operator as he stands by 

 the objective and adjusts it. The adjustment is effected by this 

 means with the greatest ease. 



Dr. Sorby at Cambridge. — The following neat reference to 

 Dr. Sorby's labours made by the Public Orator at Cambridge on the 

 occasion of conferring the LL.D. degree, may appropriately find a 

 place in this Journal which numbers so many readers " qui minuta 

 ciiriositate arcana ilia quce oculorum aciem fugiunt instrumentorum novo- 

 rum auxilio perscrutantur " : — 



" Quam magna est rerum natura, in magnis quam immensa, 

 in minimis quam magna ! Quam multa miracula, antiquis ignota, 

 illis nuper ostendit qui minuta curiositate arcana ilia qute oculo- 

 rum aciem fugiunt, instrumentorum novorum auxilio perscrutantur ! 

 Hie autem ille est qui, et terrestrium et de cfelo delapsorum lapi- 

 dum investigandis elementis primis, primus inter Britannos talium 

 instrumentorum usum accommodavit. Nuper Societatis Geologicfe 

 presses electus, annorum triginta labores oratione cumulavit in 

 qua vere marmoreum sibi monumentum exegit.f Illud vero acutissi- 

 mum quod crystallis etiam minutissimis exploratis in quibus (ut fit) 

 pars altera est aquse plena, altera aeris quoque vacua, olim indicavit 

 qua potissimum caloris temperie inclusa ilia aqua totum illud vacuum 

 implere, quo potissimitm rerum statu saxum illud, quondam ignibus 

 prorsus liquidum, primum durescere potuisset. Scilicet crystallum 

 illud (ut Claudianus ait) 



' Non potuit toto mentiri corpore gemmam, 

 Sed medio mansit proditor orbe latex 

 Auctu3 honos ; liquidi crescunt miracula sasi 

 Et conservatse plus meruistis aquae.' 



Suo phaselo vectus quot maria mox lustrabit, in terra iara pridem 

 unum saltem Argonautarum, qui terram oculis penetrabat, eatenus 

 semulatis, quod in intima saxorum materia perspicienda, ipse oculo 



* ' Zeitsch. Mikr.,' i. (1879) p. 321. 



t In allusion to Dr. Sorby's Presidential Address "On the Structure and Origin 

 of Limestones." 



