emoved from the apex, which now presents a platform of 25 feet square.
The assizes vary from two feet two inches to four feet ten inches in depth.
From five to twelve feet is the common length of the stones, except in the king's chamber.
A column is said to be monolithic, or else to consist of assizes.
A magnetized needle whose polarity is balanced so as to remove its tendency to assume any given direction.
It was in 1820 that Oersted, of Copenhagen, announced that the conducting wire of a voltaic circuit acts upon the magnetic needle, and thus recalled into activity that endeavor to connect magnetism with electricity which, though apparently on many accounts so hopeful, had hitherto been attended with no success.
Oersted found that the needle has a tendency to place itself at right angles to the wire, a kind of action altogether different from any which had been suspected.
If two similar magnetized needles are placed parallel, bu
ime scooped out, and the air-exhausting process repeated.
This plan was adopted with a bridge which crosses the Thames near Richmond, England.
Fig. 1022 is a section of the movable iron caisson used in building the piers of a bridge at Copenhagen, Denmark.
It comprises an upper chamber communicating with the air, an intermediate or airchamber, both equal and cylindrical in section, and a lower working-chamber of larger section than the foregoing, and adapted to the shape of the pier; the was gradually raised as this progressed, and when it was finished up to the water-line, the caisson with its suspending stage and tackling was removed to the site designed for another pier, where a similar operation was repeated.
Caisson at Copenhagen.
Caissons of this kind, having an open bottom and provided with air-locks, act upon the principle of the diving-bell, the pressure of air in the working chamber and air-locks being equal to that of the depth of water in which they are subme
oxide, the whole being ground into a paste.
Professor Bunsen, a few years since, introduced bichromate of potash instead of nitric acid in the battery bearing his name.
This performs well for a time, but in consequence of the precipitation of sesquioxide of chromium upon the zinc it gradually loses power.
Another modification dispenses with the porous cup, using the two liquids in mixture.
The same objection attaches to this as to the former.
In the battery of Professor Thomsen of Copenhagen, a number of plates of platinum are immersed in dilute sulphuric acid, and are, by means of an electro-magnetic motor, successively brought into contact with the poles of a single cell of Daniell.
The plates become covered by the decomposition of water with oxygen on one side and hydrogen on the other, giving rise to a powerful current in the platinum combination, which is maintained nearly constant when the contacts succeed one another rapidly and regularly.
To describe them more in d
（Carpentry.) A one-handed chopping-tool.
Hatchets of the stone age have been found with eyes for the reception of the helve.
No such perforation is found in any bronze axe or hatchet of the immense period during which the cutting tools were formed of this metal.
Bronze was always cast, and it seems wonderful that no one thought of casting it with an eye. Natural holes in stones were utilized for eyes; two flint hatchets in the museum of Copenhagen are examples.
The early history of our race is written in the tools of stone, bone, and bronze.
A few leaves from the chapters to be found in all our museums are transferred to these pages.
a is a copper celt from Waterford, Ireland, resembling in shape the earlier stone tools, such as axes, adzes, chisels, hoes, for the chase, war, carpentry, and agriculture.
b is a winged celt from Ireland, c a socketed celt from the same country.
d e f show the modes in which the celts a b
Simpheropoller surrounding apertures for the escape of gases.
If the shell-head be employed, it is provided with a fuse, so as to burst at or before the time of striking.
These rockets were first employed in the attack on Boulogne, in 1806, and again at Copenhagen, in 1807.
They were also used at the battle of Leipsic, 1813, by the British rocket troop, an organization which is still maintained in that service.
In Hale's rocket, the stick is dispensed with.
As originally made, this rocket, which in
e same year she left Savannah for Liverpool, making the trip in 22 days, during 18 of which she was propelled by steam-power From Liverpool the Savannah went to Copenhagen, Stockholm, St. Petersburg, Cronstadt, and Arundel, and from the latter port returned to Savannah, making the passage in 25 days.
The log-book of the Savannanlopen at the mouth of the Delaware.
For the break water at Cherbourg artificial stone blocks of 712 cubic feet each were immersed
The fortifications before Copenhagen are made of a concrete of broken stone and hydraulic mortar.
The sluice of Francis Joseph on the Danube, in Hungary, is built entirely of concrete.
This work ere 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
anical Value of the Distribution of Weight in the Ossicula, Trans.
Am. Otological Society, 1874.
Another step in the direction of the conveyance of sound consists in connecting a membrane in a mouth-trumpet by means of a fine cord with a similar membrane is a trumpet applied to the ear of a person at a considerable distance, say in another room.
The sounds are audible, not merely as to pitch, but are recognizable as articulate sounds.
The writer knew an officer who was with Nelson at Copenhagen, who was wounded so that his hearing was destroyed.
He was in the habit of placing a music-box against his teeth, or holding in his teeth a string whose other end was shut tightly between the lid and the box. He said he heard very well.
The experiment of connecting distant sounding-boards, so that one is made to vibrate in unison with the other, is familiar; indeed, the synchronous vibration may be obtained even by the vibrations of the atmosphere, as when the sounds of a piano are rep