The London, Edinburgh and Dublin philosophical magazine and journal of science . e same direction, will, as is proved in the last section,coalesce into a single resultant beam W travelling along theaxis of the cone, which single resultant may accordingly besubstituted for the elementary sheaf of beams. The general conclusion is :—The whole of the light emittedfrom the objective field may, by Theorem 1, be resolved intobeams of uniform plane waves ; these beams may be divided intosmall groups, each an elementary sheaf of beams; and eachelementary sheaf of beams may have a single beam substitute
The London, Edinburgh and Dublin philosophical magazine and journal of science . e same direction, will, as is proved in the last section,coalesce into a single resultant beam W travelling along theaxis of the cone, which single resultant may accordingly besubstituted for the elementary sheaf of beams. The general conclusion is :—The whole of the light emittedfrom the objective field may, by Theorem 1, be resolved intobeams of uniform plane waves ; these beams may be divided intosmall groups, each an elementary sheaf of beams; and eachelementary sheaf of beams may have a single beam substituted-for {tm—In every subsequent step of our investigation we needonly deal with these resultants—these secondary beams as theymay be called—which, though many, are limited in number. 30. Another proof of Theorem 2.—Theorem 2 may beproved in many ways, and a proof which carries the analysisof an image down to its simplest elements will be foundinstructive. Describe a hemisphere in front of the objectivefield and round its centre. Gall the point where the optic Fiff. axis of the microscope pierces this hemisphere, its passing through the optic axis may be called themeridional planes ; and the objective plane, being perpendicularto the axis of the microscope, will be its equatorial the equator of our hemisphere into seconds of arc,i. e., into 1,296,000 parts, which will afford sufficientlyminute divisions upon which the bases of elementary conesmay abut. Draw parallels of latitude also at intervals of asecond ; and draw meridians as in the figure, marking out inconjunction with the parallels of latitude the bases of theelementary cones, or rather pyramids. These becomenarrower the higher the latitude, and as soon as they haveshrunk to half a second horizontally every alternate meridianmay be omitted, until they have shrunk again till othermeridians may be omitted without any of the little sectors Dr. G. J. Stoney on Microscopic Vision, 439 bein
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