An essay on electricity : explaining the principles of that useful science, and describing the instruments, contrived either to illustrate the theory, or render the practice entertaining : illustrated with six plates. To which is added, a letter to the author, from Mr. John Birch, surgeon, on the subject of medical electricity / by the late George Adams.

George Adams Jr.

Date:: 1799

Credit: An essay on electricity : explaining the principles of that useful science, and describing the instruments, contrived either to illustrate the theory, or render the practice entertaining : illustrated with six plates. To which is added, a letter to the author, from Mr. John Birch, surgeon, on the subject of medical electricity / by the late George Adams. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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$L3] , Those reflectors that are constructed upon the principles of Newton or Herschel are about twice the above lengths in the tubes. The reflectors upon the usual Gregorian construction are made with the vertical motion upon a new principle, so as to render them more firm and steady while in use, than any reflectors mounted in the common manner. A four feet seven-inch aperture Gregorian reflector, with the vertical motion upon a new-invented principle, as well as apparatus to render the tube more steady In ob- servation 5 according to the additional apparatus of small fl. s. d. speculums, eye-pieces, micrometers, &c. from SO/, to . . 100 0 O Three feet long, mounted on a brass stand, common mount- ing 23' 2 0 Ditto with rack-work motions, improved mounting, and metals 36 15 O Two feet long, without rack-work, and with four magnify- ing powers. Improved, 13/. 13j. to 14 14 O Ditto Improved, with rack-work motions 22 1 O Eighteen inch on a plain stand 8 8 O Twelve inch ditto 5 5 O Telescopes, both refracting and rellectlng, fitted up with equa- torial, &c. motions, micrometers, adjusting,compensating, ^ &c, apparatus, for the most accurate astronomical purposes Common Microscopes, from 2r. 6<^. to 1 1 O Wilson’s single pocket microscopes, from ISi'. to 2 12 6 Compound microscopes improved, from 2/. 12s. 6d. to ... . 5 5 O New improved universal ditto 6 6 O Ditto with the most complete apparatus 10 10 O Solar microscopes In brass, improved, from 4l. 14j. 6d. to . . 6 6 O 'I'he new opake and transparent solar microscopes, with Im- proved apparatus, from 10/. IOjt. to I6 16 O Ditto of a larger size, with additional megalascopic appa- ratus, from 14/. 14.y. to I9 ig 0^ Ditto, and best compound ditto, packed together In one mahogany box ! 21 O 0 The Lucernal Microscope, as improved by Jones, exhibiting images of opake and transparent objects by night or day, in a manner singularly pleasing, brilliant, and distinct, with upwards of 100 objects, proper appa- ratus, patent lamp, ike 10 16 0 Ditto combined with a solar, compound, &c, apparatus, forming the most perfect collectfon of microscopical ap- paratus 35 14 0 A portable optical apparatus, consisting of a scloptic ball and socket, a solar microscope, Wilson’s microscope,^ a pocket compound microscope, a pocket telescope, and solar telescope, in mahogany and brass 3 13 6 Pocket microscopes for opake objects, from ids. to 2 12 6 Botannic microscopes for flowers. See. from 5^. to Ill 6 A new universal pocket ditto, adapted to all sorts of objects 1 6 0 Ditto with adjusting screw, speculums. Sec 210 O Cloth microscopes, from 2s. 6d. to 0 10 6 Magic lanthorns, from l/. 4^. to 1 8 O Sliders for ditto in great variety of subjects, each 0 3 6 A nev/ set of moveable painted sliders, shewing the funda- mental principles of astronomy, with the real and appa- \$

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