It was so with these inexpressibly minute sporules; they were not there a short time since, but they grew large enough for our optical aids to reveal them, and there they were.
Now, without discussing the real optical or anatomical value of this result as it stands, what I desire to remind you of is: 1.
To our most delicate manipulation of light, our finest optical appliances, and our most riveted attention, it was a homogeneous fluid and nothing more.
It lies on the very verge of our present powers of optical aid, and what we know concerning it will convince you that we are prepared with competent skill to attack the problem of the life-histories of the smallest living forms.
We may just mention here, that no kind of progress was made in mechanical or optical science during the first part of the sixteenth century.
He now saw, that if this were admitted, the changes it would everywhere introduce in the optical part of the planet's irregularities might perhaps relieve him from the perplexity in which the vicarious theory had involved him.
It is an invention of great utility, and grounded on optical principles, nor is it at all difficult of execution; but it must be so divulged as not to be understood by the vulgar, and yet be clear to the sharpsighted.
The geometrical and optical papers, published in the Philosophical Transactions of the Royal Society, when he was only fifteen years of age, show at least a firm groundwork of scientific knowledge.
In 1815 he received the Copley Medal of the Royal Society for one of his discoveries in optical science; and soon after was admitted a Fellow of that body.
If now we compare the eye with other optical instruments, we observe the advantage it has over them in its very large field of vision.
No stress whatever needs here to be laid upon minute anatomy, as, for instance, of the eye: it signifies not, whether we do or do not understand its optical structure as a matter of science.
Speaking of the Eye as an optical instrument, he says, "Here are four conditions of things each utterly independent of the others, viz.
It is clear thus that the eye is an optical instrument.
For instance, we may think of the eye only as an optical instrument wonderfully constituted, and enumerate the parts of its visual apparatus.
Still, the fact that, however bad they may be, I can get no others, does not at all diminish their defects, so long as I maintain the narrow but indisputable position of a critic on purely optical grounds.
We have now seen that the eye in itself is not by any means so complete an optical instrument as it first appears: its extraordinary value depends upon the way in which we use it: its perfection is practical, not absolute.
The mind also refuses to surrender its own associations at the bidding of optical laws.
Then, as the refraction of water differs from that of air, the optical lenses of fishes become rounded almost like little balls.
So far as the mechanical construction of an optical chamber goes, everything seems obvious.
I am extremely glad to leave England with my last optical images so beautiful.
Truly your nervous centres are "well preserved"--the optical ones also, in spite of the cataracts and loss of accommodation!
The most noticeable thing about this last named individual was the optical fact that he had but one eye.
Thus does the present offer us only shapes for optical anamorphoses, and only our spirit is the sublime mirror which transposes them into fair human forms.
His old exasperation against the teasings practised in his own case by apes of the air, whom he could not lay hold of, passed over into a similar feeling against Liana's optical self-deception.
Hard upon the heels of the optical chariot with which the Devil threatened to run over the master, thus spell-bound in the circle of agonizing anxiety, followed a real one, wherein sat the future Provincial Director.
His optical investigations are perhaps the subject in which he most contributed to the progress of science; and the lucidity of exposition which marks his Dioptrics stands conspicuous even amid the generally luminous style of his works.
Playing billiards, accompanied by the vicious habit of pounding on the floor with the butt of the cue ever and anon, produces at last optical illusions, phantasmagoria and visions of pink spiders with navy-blue abdomens.
The reduction of the external world to subjective terms, the explanation of the optical illusion of objectivity, demands a much greater display of vain ingenuity than any theory of simple perception.
Happily, in our day, one may without great loss destroy an optical or physical instrument, it can be replaced; but what is to become of an intelligence in the hands of the fanatical believer?
We have seen elsewhere[141] that happiness and unhappiness are ex post facto mental constructions that are based upon a multitude of optical illusions.
It happened sometimes that these honest men were obstinate in their belief; but, after a certain time, they were forced to acknowledge that they had been dupes of an optical illusion.
It cleared the little furrow produced by the incessant use of thatoptical instrument, so much missed by the poor cousin, and it stopped just at the extremity of his nasal appendage.
This optical illusion evidently takes place because there are no points of comparison on these large spaces.
Cousin Benedict, however, was destined never to see those two optical attendants again, because they had been buried with the royal manikin.
Once its initial assumptions are granted, the theory undoubtedly gives simple and natural explanations of the chief optical and electrical phenomena, and in particular leads at once to Fresnel's formula given above.
Various electrical experiments also point to the conclusion that the medium in which optical and electrical effects take place is carried along with the earth in its motion.
In conclusion, it may be said that optical telegraphy, which has only within a few years emerged from the domain of theory to enter that of practice, has taken a remarkable stride in the military art and in science.
The system of opticalcommunication proposed by Capt.
It has been proposed to connect the key of the manipulator of the optical apparatus with the manipulator of an ordinary Morse apparatus, thus permitting the telegram to be preserved upon a band of paper.
Various interesting experiments have been made with a view to utilizing luminous captive balloons for optical communications.
It is therefore possible with this arrangement, and by the use of the Morse alphabet, to establish an optical communication at a distance.
From a military standpoint, its short range will evidently not permit it to compete with optical telegraphic apparatus, properly so called.
Optical telegraphy, by reason of its very principle, presents both the advantage and inconvenience of leaving no automatic trace of the correspondence that it transmits.
The projectors employed for lighting to a distance the surroundings of a stronghold or of a ship have likewise been applied in optical telegraphy.
For full ten minutes he continued his optical search over the sea,-- until not a fathom of the surface had escaped his scrutiny.
The Nipe had robbed an opticalproducts company in Miami.
Carefully he approached the rear door of the little optical shop.
This undertaking, however, was beset with very great optical difficulties, and for a long time little advance was made upon the work of preceding generations.
A much more valuable practical result of Brewster's opticalresearches was the improvement of the British lighthouse system.
The optical contrivances in the eye form an image of the planet on the retina which is necessarily very small.
It is not to be supposed that this increase is a mere optical consequence of the diminution of distance.
The very obvious explanation that the whole duplication is an optical illusion has been brought forward more than once, but never in a conclusive manner.
The fundamental facts about the heavenly bodies have been chiefly learned from observations obtained with instruments of moderate optical power, specially furnished so as to enable precise measures of position to be secured.
The instrument he is to use should be that marvellous piece of mechanical and optical skill known as the heliometer.
By an ingenious optical contrivance it is possible to place the spectra from the two limbs side by side, which doubles the apparent displacement, and thus makes it much more easy to measure.
He would then have been first, no less in the theoretical calculations than in the opticalverification of the planet's existence.
That a music teacher, busily employed day and night, should, without previous training, expect to succeed in a task where the highest mechanical and optical skill was required, seemed indeed unlikely.
Herschel had made good use of seven years' practical experience in astronomy, and he had completed a telescope of exquisiteoptical perfection, though greatly inferior in size to some of those which he afterwards erected.
Glass manufacturers seem to experience unusual difficulties in their attempts to form large discs of optical glass pure enough and uniform enough to be suitable for telescopes.
This shadow presents some anomalous features, but its curious irregularity may be, to some extent, anoptical illusion.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "optical" in a variety of sentences. We hope that you will now be able to make sentences using this word.
