Fewer telescopes have been made of this than perhaps of any other form of reflector; but in comparatively recent years the Cassegrain has acquired importance from the fact of its adoption for the great Melbourne telescope, and from its employment in the 60-in.
To the centre of this membrane is attached a small feather-fibre, which, when the reflector is suitably placed, touches lightly the surface of the revolving cylinder.
In the beginning of 1845 this great reflector was mounted and ready for work.
Focal length presented to the Royal Society by Huygens, and found that Hadley's reflector "will bear such a charge as to make it magnify the object as many times as the latter with its due charge, and that it represents objects as distinct, though not altogether so clear and bright....
The Herschelian or front view reflector is represented in fig.
After the suspension of the Reflector in 1753, he edited in the New York Mercury the "Watch Tower" section (1754-1755), which became the recognized organ of the Presbyterian faction.
Any sound (such as that of the human voice) transmitting its rays into the reflector, and communicating vibratory motion to the membrane, will cause the feather to trace a sinuous line on the paper.
Reflector completed by G.
(2) As a Cassegrain reflector, fig.
Reflector already described, but in this case the floating cylinder would be below and not above the upper bearing.
Reflector by Herschel, and later by a 13-ft.
Reflector by Johann Gottlieb Friedrich Schrader of Kiel, he made his famous observations on the surface features of the moon and planets.
Through the columns of the Independent Reflector, which he established in 1752, Livingston fought the attempt of the Anglican party to bring the projected King's College (now Columbia University) under the control of the Church of England.
The other pre-revolutionary magazines were the Boston American Magazine (1743-1747), in imitation of the London Magazine; the Boston Weekly Magazine (1743); the Christian History (1743-1744); the New York Independent Reflector (1752-1754); the Boston New England Magazine (1758-1760), a collection of fugitive pieces; the Boston Royal American Magazine (1774-1775); and the Pennsylvania Magazine (1775-1776), founded by Robert Aitken, with the help of Thomas Paine.
Gears are provided for elevating, levelling, aligning the upper and lower optical systems, adjusting the inclination of the reflector and rotating the mast around a vertical axis so that observations may be made and azimuth angles taken in all directions.
Focus, and in 1789 his great reflector of 4 -ft.
(I) As a Newtonian reflector, fig.
In Lassell's instrument (a reflector of the Newtonian type) the observer is mounted in the open air on a supplementary tower capable of motion in any azimuth about the centre of motion of the telescope, whilst an observing platform can be raised and lowered on the side of the tower.
(4) As a Cassegrain reflector, for use with a spectroscope mounted in place of the photographic plate, fig.
The same observation can be made with the cone of rays of a reflector, and in the same way the fine rain-drops upon a dark background and the fixed stars in the sky become visible.
This body appears to be the source of light, and has behind it a reflector formed of concentric lamellae, while, in front, in some cases, there is a refracting lens.
Aperture at his seat, Birr Castle, Parsonstown; and in February 1845 his celebrated 6-foot reflector was finished.
In 1783 he completed his reflector of 18-1 7 Din.
(3) As a Cassegrain reflector, for photographing the moon, planets or very bright nebulae on a large scale, as shown in fig.
Perrine with the Crossley reflector in 1904-1905, and the third at Greenwich in but the imaginative side of knowledge had also potent representatives during the latter half of the 18th century.
In recent years no noteworthy refractors have been mounted on Great this plan; but type A has been chosen by Grubb for the Me!- great Melbourne reflector, of 48-in.