of Leyden, Descartes (1596 – 1650), and Leibnitz (1646 – 1716) stated the doctrine of refraction more or less fully; and Grimaldi, an Italian painter, demonstrated the ellipticity of the sun's image after refraction through a prism; Newton (1642 – 1727) determined that it was owing to the difference in the refrangibility of the respective portions of the rays.
Newton supposed that refraction and dispersion were indissolubly united, but Dollond demonstrated that by using two different kinds ofazing wood, which was burnt in the lantern in a cresset.
Coal was afterwards substituted.
The smoke rose through an opening 18 inches in diameter in the dome of the lantern, passed into a finial chamber above, and escaped by side openings.
In 1727, the lantern was destroyed, and an iron one substituted by M. Betri.
In 1780, the catoptric system of lighting was introduced by Borda, an Argand burner being placed in the focus of a parabolic mirror formed of copper plated with silver.
ourant, by James Franklin, a brother of the Doctor.
Andrew Bradford founded a paper at Philadelphia in 1719, and his father, William Bradford, issued the first newspaper published in New York, the New York gazette, in 1725.
From this period they multiplied rapidly in the Colonies.
The common name Gazette is derived from the name of a Venetian coin, worth about a cent and a half, and which was the price of the Venetian newspaper first published.
The Maryland gazette was established in 1727 or 1728; the Virginia gazette, 1736; the Rhode Island gazette, 1732; South Carolina gazette, 1731 or 1732; Georgia gazette, 1763.
The first paper in New Hampshire was published in 1756, but in the adjacent State of Vermont none existed prior to 1781.
After the Revolution, the history of newspaper progress becomes identical with that of the nation, the printing-press keeping closely in the van of Anglo-American civilization.
The honor of publishing the first paper west of the Alleghan
Then two halfcon-volutions of a double-threaded screw were used.
Since that time the tendency has been to reduce the length of the spiral.
We find notices of the suggested or experimental use of the screw-propeller by Hooke, 1680; Duquet, 1727; Pancton, 1768; Watt, 1780; Seguin, 1792; Fulton, 1794; Cartwright, 1798; Shorter, 1802.
The idea of propelling vessels by a screw in lieu of oars is mentioned in the Machines et Inventions approuvees par l'academie Royale des Sciences depuis 11727 jusqu à 1731.
Franklin suggested the same thing.
Lyttleton's English patent, in 1794, for an aquatic propeller consisted of a screw of one, two, or more threads wrapped around a cylinder, and revolving in a frame placed at the head, stern, or side of a vessel.
The credit of the first application of the screwpro-peller for marine propulsion is undoubtedly due to Colonel John Stevens, of Hoboken, N. J. In 1804, he constructed a boat with twin screws, which attained a very considerable
moon m′; the bent stem on which the latter is mounted is connected with an eccentric ring, causing it to move in an elliptic orbit around the earth; it has also a friction-wheel, which, traveling around the inclined edge of the disk B′, produces an alternate ascent and descent of the moon, illustrating its changes of declination; the parts by which the moon is revolved are also so adjusted as to exhibit the retrogression of their nodes.
See also Orrery, pages 1577, 1578; planetarium, page 1727.
A means for transmitting power, originated by Hirn of Logelbach, in which high speed is employed to give the momentive effect of great mass.
The motor is made to give a high velocity to a pulley-wheel, and this wheel is employed to carry a cable which passes over another pulley at the point where the power is to be applied for use. The cable may be lighter in proportion as the velocity with which it travels is greater.
Theoretically, there is no limit to th