ADDENDA TO LIST 



CONSTRUCTED BY 



ANDREW PRITCHARD, 



!L[l m A M OJ) F A T 00 K d ^ 

 162, FLEET STREET, LONDON. 



1. PRITCHARD'S Apparatus for illustrating the Interference of Light, with 



Telescope and 100 Screens ............ 15 15 



2. - ditto, with 50 Screens ...... ^ . . . . 10 10 



3. - ditto Pocket Apparatus .......... 086 



4. - improved Eye-piece Polariscope, with Reflector . . 220 



This instrument exhibits the colours more intense, and the rings better defined, 

 than the Slider Polariscope, invented some years ago by Mr. P. and now generally 

 used. It can be applied to any compound Microscope. 



5. - improved Polarizing Apparatus for the Microscope .. 1 11 6 



By Mr. P.'s new arrangement of the Prisms, the field of view is greatly extended, 

 and any eye-piece can be used. 



6. - ditto ditto large Prisms and a double image one . . 440 



7. The Apparatus 4 and 5 fitted to Microscopes .. .. .. .. 2126 



8. Stereoscopes ................ 0150 



This curious instrument, invented by ProfessorWheatestone, illustrates the pheno- 

 menon of single vision with two eyes. 



9. Heliostats, with spring Clock, for fixing the sun's image in any position 880 

 10. Pritchard's improved Gas Microscopes . . . . . . <18 to --- 



1 1 . - ditto ditto with polarizing and interference Apparatus --- 



12. - - new portable Gas Generators and Holders . . . . 880 



This apparatus generates with one charge only sufficient gas for several exhibitions, 

 and retains it any length of time ready for use. 



13. Prism Telescopes for shewing the lines in the Spectrum . . . . 770 



14. Pritchard's Vertical Microscopes, single, doublet and triplet 5 5s. to 10 10 



The doublets and triplets are all constructed with thin piano, convex lenses, and 

 not common globules. 



15. - Achromatic Microscopes [see Microscopic Illustrations] 



16. Improved Magic and Phantasmagoria Lanthorns. . \ 12s. 6d. and 3 13 6 



Sliders of Astronomical, Natural History, Costume, and Comic subjects. 



17. Selenite Ornaments and Wedges for polarized Light .. .. .. 076 



18. Pairs of Lenses for exhibiting Newton's coloured Rings . . . . ' 10 



19. Nichol's improved dumpy single-image Prisms, each .. 7s. 6d. to 14 



20. Pritchard's new Fine-Adjustment Microscope Bodies .. .. .. 1 11 6 



This construction is simple, more precise in its action, and of more general utility 

 than any contrivance yet invented for the purpose. 



21. Microscopic Objects, Is. each and upwards, or in cases at 6s., 15s., 21s. and 560 



These objects consist of thin sections of Recent and Fossil Woods, Coal, Jet, Char- 

 coal, Oolites, Flint,Teeth, Bone, recent and fossil. Insects and Dissections preserved in 

 Balsam. Zoophites, Ferns, Algse, Fuci, Mosses, Shells, Scales, Ditto in Flint ; Fossil 

 Infusoria; Crystals, Madrepores, Sponges, Tests, &c. These are prepared in a very 

 superior manner, and many of them cannot be had through any other source. 



22. Specimen Cases, containing Examples of the above, each 8s. 6d. and 15 



ACHROMATIC AND REFLECTING TELESCOPES. 



OPERA GLASSES, Single, Double, and Solid. 

 SPECTACLES IN EVERY VARIETY OF MOUNTING, WITH CRYSTAL AND CLASS LENSES. 



BAROMETERS AND THERMOMETERS. DOUBLE IMAGE PRISMS. 



FRESNEL'S RHOMBS. BARTON'S IRIS BUTTONS. TOURMALINES. POLISHED CALCAREOUS SPAR. 

 INTERFERENCE MIRRORS AND PRISMS. 



antr ii-Hcrctfcogu ^pparatutf of all fctntttf. 



J. Darkiu, Printer, 3, Grove Cottages, Hulloway. 



