£. s. d. 



31. Object glasses, Achromatic, foreign (seconds) 1 10 



32. „ „ >, (^st) 



33. „ » English (best) 



For the foci, apertures, and powers, given by achromatic object-glasses, 



see M. I. 



34. Spherule magnifiers, from l-30th to l-300th of an inch focus 



35. Single, Doublet, and Triplet Glass Magnifiers, mounted 



Focal Magnifying Power. Single Lenses. Doublets. Triplets, 



lengths in „., j, j it . j V * d 



parts of inch Linear. Superficial. £. «• d. £. s. d. t. s. a. 



One inch 10 ... 100 times ... 4 6 ... 7 6 ... — 

 l-2d ... 20 ... 400 — ... — ••• — — ~ 

 l-3d ... 30 ... 900 — ... — ... — - — 

 l-5th ... 50 ... 2500 — ... — ••• — — — 

 l-10th .. 100 .. 10000 — ... 9 ... 1 ... 1 10 

 l-20th ... 200 ... 40000 — ... 12 ... 1 10 ... — 

 l-30th ... 300 ... 90000 — ... 16 ... — ... — 

 l-40th ... 400 ... 160000 — ... — ••• — — — 

 l-50th ... 500 ... 250000 — ... — — — ••• — 

 l-60th ... 600 ... 360000 — .. — — — ••• ~ 

 l-80th ... 800 ... 640000 — ... — ••• — ••• _ 



36. Single and Doublet Diamond, Sapphire, and Garnet Magnifiers 



37* Pocket Magnifiers, in tortoise-shell frames, various 



gg' ' 2 lenses, in neat frame ., 



39 " ,, and 1 Coddington 



4q\ Coddington mounted, in silver 



41. M Stanope 



40' in pearl and silver •••• 



„ 3 crystal lenses, in best flat mounting 2 2 



44 ' fJ 2 crystal lenses, and 1 tourmaline ... 2 12 6 



45' Tourmalines, mounted in silver and pearl, for the pocket ... 18*. to 1 10 



46*. Telescopes, Achromatic, day and night, 1 foot, 2 feet, and 30-inch ... 



47 )( Astronomical, 3£ feet and upwards ... 



48 * ■Reflecting, from 2 to 8 inches diameter 



49 ' # " Stands, brass, for the table, various 



5 0> ' „ wood, improved garden • 



gj t ,, equatorial \ • 



52* Microscopic Gnoneometers, for measuring the angles of object-glasses 

 and specula, (M. C. 223) 



53. Machines for making thin sections of woods 



54. Knives for ditto • •'."'*',' 



55 Solid Pyramid Opera-glasses, mounted in silver 



56 Prism Telescopes, for exhibiting Fraunhofer s lines 



5/ Pocket Apparatus, for showing the interference of light 



5s! Telescope and ditto „ „ » complete 



59. ,, „ „ „ „ improved mounting 



60. Heliostats, with clock-work 



61. Gowland's Self-adjusting Artificial Horizons V^TT a m n 



62. Polariscopes, with 5 to 8 crystals £%• f to 4 lu n 



63 ?> Pritchard's improved slider ,^1. 8s. to 4 4 



This Polariscope enables the possessor to examine sections of any 

 crystals that present themselves, and to augment their number at any 

 time. 



64. Slides, containing three crystallized plates, for exhibiting the systems 



of coloured rings by the above instrument, each slide ... 10s. 6d. to 1 1 



65. Japanned Reflectors, for polarizing light • •• 4 6 



66. Polarizing Prisms mounted to Microscopes for shewing coloured 



tints, &c. in minute crystals, (M. I.) 30s. to 4 4 



6 7 Stage, Double Object-glass/Tourmaline, &c. for shewing 



unannealled glasses, selenite devices, system of rings, 

 structure of quartz, &c. by the Microscope, (M. I .) ... 



