 | Edinburgh encyclopaedia - 1830 - 856 pages
...is employed for the purpose of illuminating the object should have as small a diameter as possible. In the daytime it should be a single hole in the window-shutter of a darkened room, and at night it should be an aperture placed before an Argand lamp. Sol» 7. In all cases, and particularly when... | |
 | Denison Olmsted - Physics - 1832 - 402 pages
...and look horizontally, parallel markings or lines will be seen most perfectly when their direction is vertical ; viz. the direction in which the lubricating...the object should have a very small diameter. In the day time, it should be a single hole in the window shutter of a darkened room, and at night an aperture... | |
 | Denison Olmsted - Physics - 1835 - 374 pages
...and look horizontally, parallel markings or lines will be seen most perfectly when their direction is vertical ; viz. the direction in which the lubricating...the object should have a very small diameter. In the day time it should be a single hole in the window shutter of a darkened room, and at night an aperture... | |
 | Sir David Brewster - Microscopes - 1838 - 432 pages
...and look horizontally, parallel •markings or lines will be seen most perfectly when their direction is vertical ; viz. the direction in which the lubricating fluid descends over the cornea. 6. Every part of the object should be excluded, except that which is under immediate observation. 6.... | |
 | David Brewster - Light - 1841 - 432 pages
...and look horizontally, parallel markings or lines will be seen most perfectly when their direction is vertical ; viz. the direction in which the lubricating...which is under immediate observation. 6. The light wliich illuminates the object should have a very small diameter. In the day-time it should be a single... | |
 | Denison Olmsted - Physics - 1844 - 618 pages
...and look horizontally, parallel markings or lines will be seen most perfectly when their direction is vertical; viz. the direction in which the lubricating...diameter. In the daytime it should be a single hole in the window shutter of a darkened room, and at night an aperture placed before an argand lamp. 7. In all... | |
 | Denison Olmsted - Physics - 1844 - 610 pages
...and look horizontally, parallel markings or lines will be seen most perfectly when their direction is vertical ; viz. the direction in which the lubricating...diameter. In the daytime it should be a single hole in the window shutter of a darkened room, and at night an aperture placed before an argand lamp. OPTICS. Fig.... | |
 | David Brewster - Optics - 1845 - 436 pages
...and look horizontally, parallel markings or lines will be seen most perfectly when their direction is vertical ; viz. the direction in which the lubricating...diameter. In the day-time it should be a single hole in tha window-shutter of a darkened room, and at night an aperture placed before an Argand lamp. 7. In... | |
 | Denison Olmsted - Physics - 1850 - 624 pages
...up and look horizontally, parallel markings or lines will be seen most perfecMy when their direction is vertical ; viz. the direction in which the lubricating...object should be excluded except that which is under immt diate observation. 0. The li^ht which illuminates the object, should have a very small diainelcr.... | |
 | Joseph Henry Wythe - Microscopes - 1851 - 204 pages
...and look horizontally, parallel markings or lines will be seen most perfectly when their direction is vertical; viz., the direction in which the lubricating...In the day-time it should be a single hole in the window shutter of a darkened room, and at night an aperture placed before an Argand lamp. 7. In all... | |
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The worst of all positions is that in which we look downward vertically. 4. If we stand straight up and look horizontally, parallel markings or lines will be seen most perfectly when their direction is vertical; viz. the direction in which the lubricating... 
