The microscope and its revelations / by the late William B. Carpenter.

  • William Benjamin Carpenter
Date:
1901
Catalogue details

Licence: In copyright

Credit: The microscope and its revelations / by the late William B. Carpenter. Source: Wellcome Collection.

    1208/1278 (page 1136)
    4 grammes = 15 (drachm) (apothecaries’) ; 7 grammes = 4 dr. (drachms) (avoirdupois). 5 kilogrammes = 11 lb. (avoirdupois). 50 kilogrammes = 1 cwt. Robert's 19 Band Test Plate Band Lines per inch Band Lines per inch 1 11259*5 15 90076-1 5 10 33778-5 61927-3 19 112595*1 Difference between each band = 5629*75. Nobert's last 20 Band Test Plate Band Lines per inch Band Lines per inch 1 11259-5 1 15 168892-7 5 10 56297-6 112595 1 20 225190-3 Difference between each band = 11259*5. Convenient Formula for Lantern Projection or Enlargement and Reduction. Let D be the distance of the screen, and d the distance of the object from the optical centre of the lens, F the equivalent focus of the lens, M the magnifying power or ‘ number of times ’ for enlargement or reduction, then— D = F (M + 1); + F- D M+lL ’ F. > Example : It is required to project by a lens of 6 inches equivalent focus a slide having a 3-inch mask so that it may give a 10-ft. disc, what must be the distance of the screen ? Here M the magnification will be 40 times. D = F (M + 1) = 6 (40 +1) = 246 inches = 20£ feet. Note, in a double combination the optical centre may be assumed to be half way between the lenses. To reduce, interchange the object and the screen. Royal Microscopical Society's Gauges Substage Eyepieces, No. 1 >» » 2 »> >* 3 55 55 4 1-527 inch •9178 ,. 1-04 „ 1-27 1-41 = 38*786 mm. = 23-800 „ = 26-416 „ = 32-258 „ = 35-814 For the screw of the objective and nose-piece the Society supply, at cost price, a sizing die and plug, also screw chasers. They do not, how- ever, supply standard screw gauges. Full particulars regarding the screw will be found in the ‘ R.M.S. Journal,’ 1890, p. 389.