expensive, especially the larger sizes.
Dr. Dick mentions one of 5 1/2 inches aperture and 5 1/2 feet focal length, which cost 200 guineas.
Plopl, an optician of Vienna, has recently invented an improvement on the achromatic, which he calls the dialytic telescope, in which the several different kinds of glass composing the compound object-glass are not placed close together, but at regulated distances apart.
This arrangement allows a shortening of the tube.
Chester More Hall, of Essex, England, invented the achromatic telescope in 1729, but did not make it public.
Dollond had to invent it over again.
An instrument for determining the purity or strength of acids, founded on the principle that the strength of any sample of acid is proportionate to the quantity of alkali which it will neutralize, or the quantity of carbonic acid gas which it disengages from a carbonate of soda or potash.
An accurate and economical apparatus for this purpose is proposed by Dr
crushing machine, consisting of a pair of cast-iron rollers, for grinding roasted ore.
（Mining.) The central portion or stratum of a mass of ore in the process of washing.
A porous earthen water-pot, used in India in refrigerating.
A small table-furnace.
It may be of iron or of a black-lead crucible, fitted with air-holes and a grate.
（Nautical.) A kind of vessel employed in the Newfoundland fisheries.
Named from Chebacco (now Essex), a town in Massachusetts.
Also called a pink-stern.
1. (Fabric.) A pattern produced by crossing stripes in the warp and the weft.
The stripes may be of varying colors, or varying thickness, or both.
2. An East-Indian screen or sun-shade made of narrow strips of bamboo, four to six feet long, with connecting cords, and hung before doors or windows of apartments.
3. A card, plate, or tag in duplicate, used to identify articles placed promiscuously with others.
their system of dikes.
Walcheren is formed of ten islets united into one.
At the middle of the fifteenth century, Goeree and Overflakkee consisted of separate islands, containing altogether about ten thousand acres. By means of above sixty successive advances of the dikes, they have been brought to compose a single island, whose area is not less than sixty thousand acres. The first dikes of Holland are attributed to the Romans.
A levee 6,000 yards in length defends the Romney Marsh, Essex, England, from overflow by the sea. The levee was made during the occupancy of Britain by the Romans, and is kept in good order, 24,000 acres of rich land being thus obtained.
The fresh water in the ditches passes off at the lowest state of the tide by three sluices.
In Lincolnshire, England, 400,000 acres of feverand-ague breeding swamp-land have been transformed into fields of wheat, barley, and oats, and excellent meadows.
An instrument for indicating a hor
track like that of a mole, establishing a duct to lead water from the subsoil, pressing the earth away, but not purposely disturbing the surface.
It is said to have been invented by Adam Scott (British), and will be easily understood by the illustration.
The work is all beneath the soil, in positions where a surface drain is inadmissible, the thin colter to which the mole is attached only making a mark which is soon obliterated.
It was used in draining the marshes of Essex, England, during the latter part of the last century.
In a modification, the mole is attached by a short chain to the bottom of the sharp standard, to permit the mole to avoid obstacles, and by lessening its rigidity increase the ease of traction.
Fig. 3207 is a tile-laying mole-plow.
The cutter-bar is pivoted to the carriage, and adjustable to vary the presentation of its foot by means of an upper beam to which it is attached and braced.
A mole trails behind the
Vecchia, Ostia, and Antium, as well as those of many modern ports, especially in Europe, whose small rivers afford but narrow refuges.
The Roman embankments of Essex and Lincolnshire, in England, were steep mounds of earth, defended by rows of piles, the intervals between the rows being filled up with chalk.
Modern embankm off side, whether on the side-saddle or pillion.
Queen Elizabeth's side-saddle.
The side-saddle of Queen Elizabeth is still preserved at Horeham Hall, Essex, England.
The pommel is of wroughtmetal, and has been gilt.
The seat is a velvet cushion.
I did borrow a very fine side-saddle for my wife. — Pepys, 1661.
Sidelian systems of drainage, though the facilities there are not great, as the tides of the Mediterranean have a much smaller range of elevation.
The Romney marsh, Essex, England was obtained from the sea nearly 2,000 years back, and consists of 24,000 acres. The water is kept back by a levee 6,000 yards long, and the fresh water f