"similar property," so as not to be construed to cover on stock or articles excluded in the policy.

On building forms, when machinery is included, should read: "pertaining to the service of the building or the furnishing of power therein" so as not to be construed to cover manufacturing machinery. When fixtures are included, should read: "belonging to the building" or read "permanent fixtures" so as not to cover store fixtures.

FORSITE—An explosive material. A foreign make of nitroglycerine. Considered more dangerous than dynamite. FOUNDATION WORK-Foundation work calls for the best engineering skill, and the design and construction involved requires much study, as each problem demands a special solution. The best condition from an economical point of view is to have the level rock just below the cellar floor of a building; if the rock is higher the expense of excavating is large and if lower the footings must be carried to bed rock. Ordinary ground will maintain safely a load of 2 to 4 tons per square foot, dry clay from 4 to 6 tons per square foot, and gravel from 6 to 10 tons per square foot. Having these figures in mind, the necessity for footing buildings on good bed rock will readily be seen if we consider the fact that one of the New York skyscrapers weighs approximately 120,000 tons, with a wind pressure on building surface computed at 40,000,000 pounds. The cellar flooring of high buildings usually runs from 30 to 45 feet below the street, and if rock is not encountered at that depth, it becomes necessary to foot the foundations on concrete piers sunk to meet the bed rock; and if the rock is below the water level, or at a considerable depth below cellar excavation, the only known way to reach it is by means of the pneumatic caissons. These caissons are simply air-tight bottomless boxes, rectangular or cylindrical in cross section, and equipped with a steel reinforcement on bottom which is known as the cutting edge, the interior being large enough to accommodate a gang of men whose duties are to excavate the space within the area which it covers.

Prior to putting the caisson in place, a pit sufficiently large to allow for its entry is dug in the ground on the site

which the finished pier or monolith will occupy, a derrick is installed and the caisson seated accurately in place to a depth usually 6 feet below the main excavation. When in place the caisson is provided with a strong decking which allows a height of about 6 feet for workmen within the chamber. On top of the caisson decking vertical sections of air shafts are set up, these sections being usually circular in form, three feet in diameter, made of steel plate, each section measuring about 10 feet in length, and forming a means of passage to the working chamber for men and material.

The air lock is placed at top of shaft and usually consists of a steel cylinder about 5 feet in diameter, 7 feet high and bolted in position.

There are two doors in this chamber, one at the top and one near the bottom; an attendant is stationed on a platform near the upper door, whose duty it is to regulate the air pressure, attend to signals from working chamber and open and shut the air-lock doors as required.

When the outer door is opened, the inner door is closed, and vice versa, thus retaining the pressure in the caisson. Signal is made by whistle operated by compressed air within the chamber, a valve and the necessary piping being provided for this purpose.

A ladder is installed within the shaft and workmen travel to and from the working chamber by this means.

Excavated matter from working chamber is loaded in small canvas bags and carried by workmen to air lock, or it is blown out by the compressed air through special pipe, but these methods have been improved on recently and it is now possible to use half a cubic yard bucket without interfering with the caisson efficiency.

When the caisson and its appurtenances are put in place, concrete is poured around the air shaft so as to form slabs about 12 inches thick, this having sufficient strength to support a mass of wet concrete on caisson walls; sections of airshaft are added and concrete is filled within the forms in 5 foot courses until the pier is built up to about one-half its full height. As the top of the piers are to be sunk below the temporary surface of excavation they are enclosed

within coffer-dams placed 3 or 4 feet beyond, these cofferdams serving to exclude the earth from the column piers until such time as the open excavation is completed.

Forms are set up within the working chamber and concrete is built up to the desired height, after which it is sunk through the water-bearing ground, compressed air being used as the sinking progresses below water level, when another section of concrete is added, and so on until the anchorage point has been reached.

Owing to frictional resistance it is necessary to use cast iron blocks to weight the caisson for the purpose of sinking and this, in addition to the weight of the caisson, forces the work downward until the footing is reached, when the surface of the rock is cleaned and leveled, after which the whole interior of the caisson and shaft connecting the working chamber with the atmosphere is filled with concrete well rammed into place, thus forming a monolith upon which to support the superstructure.-(Robert H. Pearson.)

FOUNDATIONS-The bases of walls, piers, columns, etc., directly supported or kept in equilibrium by the earth. FOUNDATIONS FOR SKYSCRAPERS are sometimes laid as follows: Heavy, hollow steel piles are driven through quicksand and to rock. They are then cleaned out with compressed air and then two-inch steel rods inserted to act as reinforcement for the concrete which will eventually be poured in. This system of foundation work is used because it is much quicker than the former method of sinking an open pit to rock.

FOUNDRIES-Usually large area frame buildings. Hazards are pattern and flask making, preparation of the mould including core making, melting and reduction of the metal to a proper fluidity, pouring the molten metal into the mould, cleaning and finishing the casting, also core ovens and painting iron or wood patterns. When casting, a man should be stationed on the roof to detect flying sparks alighting on the roof or on nearby structures. Casks of water with fire pails should be placed every fifty feet over entire roof. There should be 12 inches clearance around floors or roof where stack from melting furnaces passes through. In case

FRAME ROWS

287 of fire, no water should be thrown on molten metal as this produces oxyhydrogen gas and is apt to cause a dangerous explosion scattering the molten mass. Carbon dioxide is a very good extinguisher, providing the seat of the fire can be enclosed. Brooklyn, New York City, has recently experienced a number of fires in this class. See Core Ovens and Cupola.

FOUNDRY FLASKS-Frames are of wood or iron, four sided, without top or bottom. Used to hold the sand moulds in position. Wooden ones frequently become charred from molten metal and losses occur from storing these flasks inside of buildings or against wood partitions where hidden sparks break out into fire.

FOUNDRY SAND "Water-proof" sand used by founders when casting in sand moulds is composed of ground resin, flour and a secret white powder which prevents the molten lead from adhering to mould. Process is grinding, mixing and heating resin by direct heat. Non-hazardous.

FOURDRINIER MACHINE-A paper-making machine in which the pulp is screened and made into sheets. See Paper Mills.

FRACTIONAL DISTILLATION-A process of distilling a mixture of several liquids having different boiling points, for the purpose of separating them from each other.

FRAME-A term used when pieces of timber are put together so as to form a truss or other structure.

FRAME Frame.

CONSTRUCTION-See

Balloon and Braced

FRAME ROWS-Many of these rows have open spaces called cock-lofts, roof spaces or small attics, which are open from one building to another. This space is between the top floor ceiling and the roof. It may be from 6 inches to 5 or 6 feet in height. Besides containing considerable dust and shavings left at the time the building was erected, they are sometimes used for storing old mattresses and junk of all kinds. Fires in these concealed spaces are hard to locate and extinguish. The tendency of a fire to spread through these spaces is greatly increased by the pressure of the air and hot gases produced by combustion. Hot

gases always rise, therefore the danger is greater directly under the roof. Partitions of incombustible material extending to under side of roofboards should be placed on each side of the studs between buildings in roof spaces. The fire record is very bad. See Attics; also Roof Spaces, CockLoft, and Brick-filling.

FRAMING AND TIMBER WORK-See Braced Frame and Balloon Frame.

FRAUD-See Misrepresentation.

FREE WAREHOUSES-See Storage Stores (bonded and free.)

FREEZER-In cold storage risks, term used to designate temperatures from 10 deg. F. above zero to 10 deg. F. below zero. See Sharp Freezer.

FREEZING WEATHER-See Fire Appliances; also Fuel. FRENCH POLISH is a polish formed by dissolving shellac in spirits of wine.