light upon it are conveyed along the opticnerve to the brain.
With felicity he explains that we see single when we use both eyes, because of the formation of the visual images on symmetrical portions of the two retinas. — Draper.
The camera-obscura of Leonardo da Vinci, b. 1452, was an imitation of the mechanical structure of the eye.
Samuel Pepys, in His Diary, records a conversation with Dr. Scarborough on board the Charles, formerly the Nazeby, on the voyage of Charles II.
from the Hague to Dover, May 24, 1660. Dr. Scarborough remarked that custom taught children to direct the axes of the two eyes convergingly upon an object, and presumed that the visual image of but one eye was appreciated at a time.
Dr. Scarborough does not seem to have deduced from this that the images differed, and thus imparted the sensation of rotundity or saliency to the object, nor the other fact that the angle of convergence of the axes gave the impression of distance.
He came very near to these
road after nightfall.
In 1667 the lighting and police arrangements of Paris were improved; the project was that of the Abbe Laudati, and was legalized in 1662.
In 1671 the lamps were ordered to be lighted from the 20th of October to the end of March, having previously been kept lighted only during the four winter months; at this time the lamps were kept burning on moonlight nights as well as others.
Their number in 1771 was estimated at 6.232.
Amsterdam had street lanterns in 1669; The Hague, 1678; Copenhagen, 1681; Hamburg, 1675; Berlin, 1682; Vienna, 1704; Birmingham, England, 1733.
For lighting by gas, see gas.
In the example, the glass is in a single piece, flaring at top, and having an opening at the bottom to receive the burner.
The cover, to which it is attached, is conical in shape, is supported by four rods affixed to the top of the lamp-post, and is capped by a perforated hood.
James L. Ewin's street-lamp has a supply of naphtha or other oil
o a gale, it was cut when 16 miles had been paid out. It was subsequently recovered in 1854, the depth of water being 150 fathoms, and found in good preservation.
i and j are the cables connecting Dover and Ostend, and Portpatrick and Donaghadee.
These two cables are precisely similar in size and general construction, each having six wires; some improvements, however, have been introduced into the latter.
k, is the shore end of the cable between Orfordness and the Hague.
Each cable is composed of a single wire, the whole being brought together near the shore and twisted into one.
l, the cable between Prince Edward's Island and New Brunswick.
m, that across the Great Belt, in Denmark.
n, that across the Mississippi at New Orleans, on the Balize line.
Malta and Alexandria cable.
The Malta and Alexandria cable (a b, Fig. 6244) is composed of seven copper conducting wires, over which are three layers of gutta-percha and one of tarred yarn, th