This is the gnomon arranged in the dome of the Cathedral by the shadow of which it is said that he could determine midday to within half a second.
Gilii laid down the meridian line in front of St. Peter's with the obelisk as a gnomon and the readings of the seasons by the length of the shadow.
It may be said in passing that Toscanelli's gnomon was later improved by Cardinal Ximenes of Spain, showing that these cordial ecclesiastical relations with science were not confined to Italy.
The gnomonic projection derives its name from the connection between the methods of describing it and those for the construction of a gnomon or dial.
Defn: The space included between the boundary lines of two similar parallelograms, the one within the other, with an angle in common; as, the gnomon bcdefg of the parallelograms ac and af.
Those which indicate other hours have a gnomon with its edge parallel to the earth's axis and inclined to the horizon at the angle corresponding to the latitude of the place in which the dial is fixed.
The gnomon shadow of Jack's Mountain had spread over the entire valley, and its southern limb had crept up Chigringo until its sharply defined line was resting upon the Massingale cabin.
That of Eratosthenes by the Sunne beames, and a shadow of a stile or gnomon set vpon the Earth, is as bad as the other.
Accordingly, it is not surprising to find that the invention of the gnomon is also attributed to Anaximander, for without some such instrument it would have been impossible for him to have made any map worthy of the name.
Hadley had invented the sextant, by which the sun's elevation could be taken with much more ease and accuracy than with the old cross-staff, the very rough gnomon which the earlier navigators had to use.
Nor is it likely that he possessed the requisite knowledge for calculatinggnomon measurements unless they were taken either at the solstice or the equinox.
In the case mentioned above the gnomon was a vertical column raised on a plane.
There were also from great antiquity, Scioterical or Sun Dials, by the shadow of a stile or gnomon denoting the hours of the day: an invention ascribed unto Anaximines by Pliny.
Albano punished himself with several days of voluntary absence, till the unclean clouds should have cleared away from within him which had overshadowed the gnomon of the sundial of his inner man.
The terrible motionless time had no gnomon on its dial-plate.
He stooped again, and found the gnomon and pencil correct, and pressing on the pencil hard, drew it towards him out of the groove a little way.
The shadow of the gnomon slipped the wrong way; he looked up and saw a light cloud passing over the sun.
To make sure, he raised his head and looked over the gnomon and pencil to the star, when he found that he had not been holding the pencil upright; it leaned to the east, and made an error to the west in his meridian.
When it was done the shadow of the gnomon touched the nine, so he shouted to Mark that it was nine o'clock.
He still had to stoop till he had got the tip of the gnomon to cover the North Star.
The shadow of the gnomon on the dial had moved a good way since Bevis set it up.
Bevis drew the line from the gnomon to the mark he had made the night before, this was the noon or meridian.
He drew a line with his pencil where the shadow of the gnomon fell on the circle, that was four o'clock.
The gnomon at once cast a pointed shadow on that side of the circle opposite the sun, but there were as yet no marks for the hours.
The Gnomon [A] was seen by Mr. Wylie in one of the lower rooms of the Observatory (see below).
We may suppose this gnomon to have been erected that by its aid the shadow at the solstices and equinoxes might be precisely noted, for in that view both the slab and the style were graduated.
The third machine was a gnomon [C], the height of which was twice the diameter of the former instrument, erected on a very large and long slab of marble, on the northern side of the terrace.
Each twelve month the gnomon on the literary sundial is likely to cast some shadow one will not willingly forget.
In addition to these comic or satiric shadows, the gnomon of his Sun Dial may be relied on every now and then to register a clear-cut notation of the national mind and heart.
He says, "The sun's annual course round the celestial sphere could be determined much more exactly than by any gnomon by observations made from the great gallery.
There are only two ways in which it could be attempted--one by observing the shadow cast by a vertical gnomon when the sun was on the meridian, the other by keeping a standard line constantly directed to the true north pole of the heavens.
He begged a strictly private interview with me, and I conducted him to a small room I had constructed by running two thin walls of porous stone from one Gnomon to another, and covering the enclosure with a flat roof.
I mounted the only unsealed Gnomon and shouted down into its cavernous depths.
For further reasons which I shall present in my calendar monograph, I infer that we have in this drawing a most valuable image of the gnomon and dial employed by the Sun priests for the observation of the equinoxes and solstices.
For as touching the sun-dial 91 and the gnomon 92 and the twelve divisions of the day, they were learnt by the Hellenes from the Babylonians.
The gnomon would be an upright staff or an obelisk for observation of the length of the shadow.
Thus they are south of Carthage 1300 stadia, that is, admitting that in Carthage at the time of the equinox the proportion which the gnomon bears to the shadow is as eleven to seven.
The degree of shadow from the gnomon which Pytheas states he observed at Marseilles being exactly equal to that which Hipparchus says he found at Byzantium; the periods of observation being in both cases similar.
It is evident that Syene is under the tropic, from the fact that during the summer solstice the gnomon at mid-day casts no shadow there.
He says that at that place the sun is vertical forty-five days before the summer solstice,[544] he also informs us of the proportion of shadow thrown by the gnomon both at the equinoxes and solstices.
At Alexandria at the time of the equinox the proportion which the gnomon bears to the shadow is as five to seven.
It may be that at a certain hour the gnomon casts a shadow at the designated place.
Upon the brass face appeared slightly raised Roman numerals and the triangular gnomon cast its shadow across the four.
The cause of this continual motion is the forcible suspension; for the whole gnomon preponderates in C on account of the perpendicular tangent B A; which effect becomes more marked if a globe of iron S be supposed suspended at C.
Now as the force of the entire gnomon falls in the vertex A, there would be an entire and perpetual revolution around A.
Thence it is evident that if the gnomon were entire, the force which it exerts at N would pass into the line B A still hanging over the centre.
In this I shall set forth the rules for dialling, showing how they are found through the shadows cast by the gnomon from the sun's rays in the firmament, and on what principles these shadows lengthen and shorten.
Put the gnomon back where it was before and wait for the shadow to lessen and grow again until in the afternoon it is equal to its length in the morning, touching the circumference at the point C.
Let A be the centre of a plane surface, and B the point to which the shadow of the gnomon reaches in the morning.
In the afternoon watch the shadow of your gnomon as it lengthens, and when it once more touches the circumference of this circle and the shadow in the afternoon is equal in length to that of the morning, mark it with a point.
This done, apply a gnomon to these eight divisions and thus fix the directions of the different alleys.
Then, from the line in the plane, let the line of the gnomon be divided off by the compasses into nine parts, and take the point designating the ninth part as a centre, to be marked by the letter A.
When the sun is at the equinoxes, that is, passing through Aries or Libra, he makes the gnomon cast a shadow equal to eight ninths of its own length, in the latitude of Rome.
The shadows of two gnats disporting on the edge of an ordinary gnomon would have seemed vastly more important, in proportion, on the figured plane of the dial, than these, our ghostly representatives, did here.
And the Emperor Augustus, returning from his Egyptian wars, brought home to Rome an obelisk which he set up as the gnomon of a huge dial in the Campus Martius.
Its gnomon is ninety feet high and one hundred and forty-seven feet long.
Diogenes asserts that the first Greek dial or gnomon was erected by Anaximander of Miletus.
STYLE—The finger orgnomon on a sun-dial whose shadow, falling on the plate, indicates the time.
And for measuring by the direction of the shadow, the vertical gnomon is more irregular still.
Since the sky is infinitely far away, the line of the gnomon would then lie parallel to the axis of the heavens.
POLOS—A basin in the center of which the perpendicular staff or gnomon was erected, and marked by lines for the twelve portions of the sun-lit day.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "gnomon" in a variety of sentences. We hope that you will now be able to make sentences using this word.
