INVERTEBRA.TA, CRYPT0GA:M[A, MIOROSCOPY, ETC. 1055 



arrangement (as shown on a larger scale in Fig. 125) the calotte 

 is attached to the under surface of the stage, — in Mr. Bulloch's plan, 

 the diaphragm plate forms part of the condenser and can thus be 

 removed at iilcasure. 



Swinging Substages. — As there seems to be a tendency to provide 

 Microscopes which have a substage with the so-called '"swinging" 

 form, we now extend the history of such instruments by giving 

 descriptions in the succeeding notes of some which we have not yet 

 described. 



Taken in chronological order, the instruments hitherto made with 

 such substages are as follows : — 



Grubb 1853-S .. See vol. ii. p. 320, and below. 



Thury-Nachet .. 1855 .. „ post, p. 1059. 



RoYSTOS-PiGOTT .. 1862-4 .. „ ;?os^, p. 1060. 



ToLLEs 1871 .. „ post, p. 1061. 



BuLLOiH 1873 „ j»08^ p. 1067. 



Zentmaver and I is^fi-RO / " vol. i. p. 197, vol. ii. p. 320, and 



Koss-Zentmayer / ■■ ' " \ a/i^t.', p. 70i. andjxjs^p. 1067. 



Tolles-Blackham .. 1877 .. „ vol. i. p. 392, and an<e, p. 520. 



Bui-Locu 1877 .. „ post,p.lOTd. 



Sidle and Poalk .. 18S0 .. „ a?i^^, p. 522. 



Beck 1880 .. „ a«i!e, p. 329. 



Swift 1880 .. „ ante,p.867. 



Grubb's Sector Microscope. — This is admittedly the earliest in- 

 strument of the kind referred to in the preceding note. Tbe following 

 description is contained in a paper read on the 26th March, 1858, 

 to tbe Royal Dublin Society,* and is entitled " On a New Table 

 Microscope, by Thomas Grubb, Engineer to the Bank of Ireland " : — 



"The instrument to which I have the honour of drawing your 

 attention this evening will bo recognized by some present as having 

 the same general and peculiar form of that which I had devised and ' 

 constructed some years since, and previous to our (Dublin) Microscopic 

 Society having merged into the * Natural History ' Society. 



" The instrument, in its original state, included, iudeed, the advan- 

 tages of extreme steadiness, an improved fine adjustment for focussing, 

 and improved safety-tube for the object-glass, with the means of 

 viewing ob.ects (placed on a horizontal stage) at the most comfortable 

 angle for vision. But it is the peculiarity of the instrument, in its 

 present state, that it removes all necessity for that subsidiary and 

 costly apparatus for illumination which those microscopists who 

 pursue delicate microscopic research find it necessary to provide, in 

 addition to the Microscope pr()j)er ; and not only this, but tbe present 

 instrntnent enables the observer to apply, with a facility otherwise 

 unattainable, without removing the eye from the instrument, without 

 any changing of parts, and by simply moving its one illuminator on 

 its sector, every kind of illumination, ^crl Uim, to an object placed 



• 'Jniim. R. Diihliii Sot.,' 18r)S; roproiliu-cd in ' Knp:l. Meoli.,' xxii. (1880) 

 p. 229. 



4 A J 



