ON THE STUDY OF THE MOSSES. 63 



The most useful cheap instrument I know is Field's School Micro- 

 scope, a very compact httle instrument having three simj)Io lenses which, 

 separate or combined, give a magnifying power of from five to forty 

 diameters. This, with the simple lenses, live box, needle, and other 

 appliances, costs lOs. 6d. ; a compound body may be added for 2s. 6d. extra. 

 This will give powers of from twenty to eighty diameters. It is well to have 

 this compound body at first, as the cabinet is then made of sufficient size 

 to hold the compound body and all the other apparatus. For an 

 additional 28. 6d. a WoUaston doublet may be added ; and, as this lens is 

 a combination of plano-convex lenses placed in such a manner and of 

 such a focus as to reduce chromatic and spherical aberrations, 

 for 15s. 6d. it is possible to possess a microscope nearly achromatic, 

 giving a power of 120 diameters, which is sufficient for almost all the 

 work which the young botanist wiU have to do. All my own earliest work 

 in mosses was done with this instrument, and I believe I learned more 

 by its aid than I have ever done with the more expensive instruments I 

 have since used. As a simple microscope it will always be useful for 

 dissecting and mounting purposes, and I can say with confidence that the 

 student who has acquired all the knowledge of structure that this cheap 

 little instrument will place within his reach will have gained such an 

 insight into the moss world as ^ill enable him to determine with a little 

 patience the most difficult of mosses. 



CASTLETON : ITS EXTINCT FAUNA AND PHYSICAL 

 SUEEOUNDINGS. 



BY THE EEV. W. H. PAINTER. 



It was upon one of the few fine mornings at the end of August 

 that I stood upon the edge of the high land overlooking the Vale of Hope, 

 and looked down upon Castleton. Before me, in the far-off distance, 

 were the hills in the direction of Sheffield that appeared to form the 

 eastward termination of the vale, while on my left appeared the sharp 

 peak of Win HiU, the more rounded summit of Lose Hill, and, very 

 close to me, the precipitous side of Mam Tor, of which more anon. 

 Then on my right were seen the road gradually winding up the hill-side 

 to TidesweU, the grey ruins of the ancient stronghold of the Peverils, 

 and the bleak moors which characterise that part of Derbyshire. 



The exact spot where I stood to view the Vale of Hope was a remarkable 

 one. It was just on the edge of the great plateau of mountain limestone. 

 Behind me stretched that formation, before me lay the Yoredale Rocks 

 overlying the same. These rocks, which take their name from the valley 

 of the Yore, or Ure, in Yorkshire, where they are most fully developed, 

 are beautifully exposed in the steex? escarpment of Mam Tor, or the 

 Shivering Mountain. Here they will be seen to consist of alternate 

 layers of sandstone and shale — the latter being impregnated with oxide 



