The microscope and its revelations . en toit, when it is used for procuring converging rays from a lamp,the lamp being placed four or five times farther off on oneside, than the object is on the other. But it may also beemployed for the purpose of reducing the diverging rays ofthe lamp to parallelism, for use either with the parabolicilluminator (§ 61), or with the side-reflector to be presentlydescribed; and the ])lane side is then to be turned towardsthe lamp, which must be placed at such a distance from thecondenser, that the rays which have passed through the lattershall form a luminous ci
The microscope and its revelations . en toit, when it is used for procuring converging rays from a lamp,the lamp being placed four or five times farther off on oneside, than the object is on the other. But it may also beemployed for the purpose of reducing the diverging rays ofthe lamp to parallelism, for use either with the parabolicilluminator (§ 61), or with the side-reflector to be presentlydescribed; and the ])lane side is then to be turned towardsthe lamp, which must be placed at such a distance from thecondenser, that the rays which have passed through the lattershall form a luminous circle equal to it in size, at whateverdistance from the lens the screen may be held.—Even wherethe large bulls-eye condenser is provided, it is weH to havea smaUer condensing lens in addition; and this, which is usually a double-Fi&. 45. convex lens, may either be mount-ed on a separatebase (Kg. 45), ormay be attachedto some part ofthe microscope-stand. ( and Beckslarge microscope,Eig. 29, two soc-kets with bind-. ing - screws, onefor the condens-ing lens, the otherfor the side-reflec-tor, are seen inthe hmV). Thiscondensing lens is sufficient by it- ^E^gE self for most ordi-nary purposes;and it may alsobe used to obtain Ordinary Condensing Lens. a greater concen-tration of the rays an-eady brought into convergence by the bulls-eye (§ 93),65. The illumination of opaque objects may be effected by reflection, as well as by refraction; and a very advantageous SIDE-EEFLECTOE FOR OPAQUE OBJECTS. 141
Size: 1421px × 1758px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, booksubjectmicroscopes, booksubjectmicroscopy
