It was with great difficulty that a sufficient number of photographic lenses was obtained for the use of military cameras, since the large lens factories of America were tied up with other war orders.
Their cameras were equipped with the only lenses available in England in the early part of the war--lenses of relatively short focus, ranging from 8 to 12 inches in this respect.
At the same time it was generally agreed that we should plan to follow the French practice as soon as lenses of greater focal length could be manufactured in this country.
The plant developed gradually, making a full line of spectacle lensesand optical instruments.
These cameras were fitted with lenses of relatively long focus--20 inches.
The optical-glass industry had never been developed in America, our field glasses being supplied with lenses of European glass, and principally German glass.
But it is difficult to see how anything but fleeting glimpses of the heavenly bodies could have been obtained with such contrivances, even if the lenses had been perfect.
The focal lengths of object glass and eyepiece will determine just what distance apart the lenses must be in order to give perfect vision.
But it is quite as important that the axes of all the lenses be adjusted into one and the same straight line, and then held there rigidly and permanently.
A HUGE LAMP The marvellous arrangement oflenses and prisms which enables the lighthouse to send out its guiding flashes, with the mechanism for turning it.
Through a hole in this box a fine pencil of light passes from a lamp, suitable lenses being used to ensure that the pencil shall have, as it were, a very fine point, producing a very small spot of light upon the paper.
Generated by powerful arc lamps, the light is concentrated by a system of lenses until it is of an almost incredible brightness, after which it falls upon the object.
If we want to form a pure spectrum we must have a narrow slit, prisms with true, flat surfaces, and lenses of proper curvature.
If quartz prisms andlenses be used, and the electric light be the source of illumination, the ultra-violet spectrum will extend to an enormous extent.
At this point we may suppose we have reached the limit of the spectrum, but if rock-salt prisms and lenses be used, the limit will be increased.
In focussing these forces through the lenses and veils [Pg 20] of sense knowledge arises; and to arrest our attention on those veils and lenses and say they are all we know, belies the facts of the case and is hardly honest.
Then, gazing through thelenses of its noble telescope, we welcomed the swift waves of light pulsating toward us from the shoreless ocean we call space.
Whose phantom features in the dome of Night Elude the keenest gaze of wistful eyes Till amplest lenses aid the failing sight, On heaven's blue sea the farthest isle of fire.
When he desires to see anything with exactness, he must use, in addition, a pair of eye-glasses which he slips in behind the lenses of his spectacles.
Further, these crustacean lenses are true lenses in the vertebrate sense, in that they are formed by modified hypodermal cells, and not bulgings of the cuticle, as in the arachnid.
Perhaps these subject-lenses have a creative power; perhaps there are no objects.
We have learned that we do not see directly, but mediately, and that we have no means of correcting these colored and distorting lenses which we are, or of computing the amount of their errors.
Life is a train of moods like a string of beads, and as we pass through them they prove to be many-colored lenses which paint the world their own hue, and each shows only what lies in its focus.
In one particular only: the latter received the rays reflected by the large mirror of the telescope, after their union at the focus, whereas the concave lenses received the same rays before that union.
The new lenses for port and harbour lights, and those used with the electric arc on board vessels of war for search purposes, introduced by Messrs.
When higher degrees of intensity are needed, a second tier of lensescan be superposed on the first, and a third and fourth added, a separate flame being in the focus of each tier.
Let the diameter of the object-glasses, which are the large lenses in the end farthest from the eye, be not less than an inch and a half.
Then, by means of a rubber band, fasten the dark glass thus prepared over the eye-end of your opera-glass in such a way that both of the lenses are completely covered by it.
If the lenses are not injured, one need not trouble one's self about the worn appearance of the outside of the instrument; so much the more evidence that somebody has found it well worth using.
At one end of this place a small swing dressing-glass, and at the other let a magic lantern be fixed with its lenses in a direction towards the glass.
Instantly an arrangement of telescopic lenses came into play within the tube of the periscope, with the result that a small portion of the view was greatly magnified upon the object card.
By an ingenious arrangement, the lenses were constructed to compensate for any deviation of the tube of the periscope from the vertical.
Under the helical headpiece that was the antenna this robot seemed to have two eyes--a new feature--but closer examination showed these to be the twin lenses of a stereoscopic motion picture camera.
Nelson, anxiously eyeing the red-crested warriors who, peering down through the blue lenses of their helmets, watched the khaki-clad aviators but made no effort to realign their retortii.
Or at least it could record what the lenses saw for its masters.
The insulating materials and even the glass of the camera lenses are possessed of the same property.
Shelton trailed him like a shadow, squinting through the square lenses of his spectacles.
The nearer the diaphragm is to the lens the less is the distortion, and some of the most modern single lenses have the diaphragm so near that the photographer is even more safe in the use of them.
Distortion produced by single lenses is due to the fact that the diaphragm is either in front of or behind them.
The use of extreme wide-angle lenses has had a disastrous effect upon the public taste in respect to architectural photography due principally to the abortions one sees exposed for sale in the shop windows of our cathedral cities.
One of the most notable of these is the "satz-anastigmat" of Zeiss, each combination consisting of four lenses cemented together and forming an excellent single lens.
The "Cooke" lens is remarkable for the simple means by which the various corrections are made, consisting as it does of only three single lenses separated from each other.
The lenses of this series, although quite new, have met with great favour amongst architectural workers.
These lenses do not cover so large a plate in proportion to their focal lengths as most of the other anastigmats, but perform excellently over the plates for which they are constructed.
There is such a great variety upon the market at the present time, that to the young photographer the buying of the right lenses is somewhat a difficult problem.
The centre, between lenses 6 and 7, is opposite the centre of the track T.
One of the lenses is provided with a focusing screen, and with it the other twelve lenses are adjusted to a proper focus without removing the plate holder behind them from its position in the camera.
When the battery is used vertically, lens 6 is usually on the same horizontal plane as the lenses of the lateral battery.
An apprentice of a Dutch optician, while playing with spectacle lenses, chanced to observe that if two of the lenses were placed in a certain position objects seen through them appeared much nearer.
In one day he had constructed such an instrument, in which he used two lenses like the lenses of the modern opera-glass.
This is an arrangement of lenses and mirrors in a tube bent in two right angles, which projects a short distance above the surface and can be turned in any direction (Fig.
You can get good portrait lenses from eight dollars a set to a very high price.
The best thing for you to do is to go to some large dealer in photographic instruments, and get a list of styles and prices of lenses and materials.
In the Huyghens or negative eye-piece the focal lengths of the field- and eye-lenses are in the ratio 3 to 1, and the distance between the lenses is twice the focal length of the eye-lens.
The Ramsden or positive eye-piece consists of two lenses of equal focal length placed at a distance apart equal to two-thirds of the focal length of either lens.
In old age, and in fact in most people after about forty-five years of age, the elasticity of the lens becomes reduced, and convex lenses become necessary to make it possible to focus near objects.
These lenses vary in magnitude, not only in different, but sometimes in the same eyes.
The number of lenses in an eye varies in different insects.
This moving reflexion of the hexagonal lenses in living insects was noticed long since in some bees (Nomada F.
The structure of both is probably the same, and their internal organization that of one of the lenses of a compound eye, and both are set in a socket of the head.
I possess a specimen in which the eye is partly black and partly white: the lenses are invisible in the black part, but very visible in the white.
The lenses of those of Xenos blaze like diamonds set in jet[1493].
As to their structure, nothing seems to have been ascertained; probably their organization does not materially differ from that of one of the lenses of a compound eye; which I shall soon explain to you.
Each of theselenses is umbilicated, or marked with a central depression.
I noticed that in addition to the microscope lenses and surgical instruments, they had taken all the fine wire.
Kyral laid out the small forged-steel tools and the coils of thin fine wire, and I unpacked my lenses and laid them out in neat rows.
Blanks equally had appeared in the rows of lenses; all of my tiny, powerful microscope lenses had vanished.
Golden eyes focused like lenses over winking jewels and gimcracks.
The shrouded ones did not move, but the lenses and the wire vanished.
It has a correctness such as no image-forming means by lenses can have.
I immediately obtained a great many specimens of glass, and spent much time in subjecting them to my lenses only to see how much fibrous appearance, or unevenness, could be brought before the eye from a smooth surface.
On these, magnified by their convex lenses of water, we pounced.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "lenses" in a variety of sentences. We hope that you will now be able to make sentences using this word.
