1902 Encyclopedia > Safes


SAFES. A safe is any repository in which valuable property is guarded against risk of loss by fire or from the attacks of thieves. The protection of valuable documents and possessions was only imperfectly effected in the charter-rooms of old mansions and in the iron-bound oaken chests and iron coffers of the Middle Ages; but these in their day represented the strong rooms and safes of modern times. The vast increase in realized wealth and the complication of financial and banking operations necessitate in our days the greatest attention to the safeguarding of securities and property. The ingenuity of inventors has, within practicable limits, effected much in safe-making; but the cunning of thieves has increased in proportion to the obstacles to be overcome and to the value of the booty at which they aim. No safe can be held to be invulnerable; for, whatever human ingenuity can put together and close, the same ingenuity can tear down and open. An impreg-nable safe would indeed be a source of greater danger than of security to its owner, for, were the key or other means of access lost or rendered unworkable, the contents of the safe would of necessity be irrecoverable. The efficiency of a safe, therefore, does not depend on absolute impregnability, but on the nature of the obstacles it presents to successful attack, and to the generally unfavourable conditions under which such attacks are made. It is common to make safes both thief- and fire-resisting, and the condi-tions necessary for the one object to a certain extent conduce to the attainment of both; but for many purposes security from the one danger alone is requisite.

The devices for baffling thieves are numerous. The safe must in the first place be made heavy and unwieldy, or otherwise it must be so fixed that it can only be carried away with the utmost difficulty. Next, the greatest obstacles to obtaining illegitimate access must be presented. To prevent fracturing a tough metal must be used in the construction, and to resist penetration by drilling metal of great hardness must be interposed. These conditions are commonly met by making the outer casing of the safe of boiler plate, backed by a lining of hard steel, over which is an inner lining of thin boiler plate, the three layers being securely bolted together by screws from within. By some makers a layer of hard metal is poured, in a fluid state, between the outer and inner casing; others case-harden one surface ; and there are numerous additional de-vices for securing the combination of hardness and tough-ness. To prevent wrenching of joints, the two sides with top and bottom of the outer shell are sometimes made out of a single plate welded at the joint, and the back and front are then attached to that shell by angle irons screwed from within. The frame upon which the door hangs and into which the bolts shoot is made of great strength, with special precautions to prevent the wrenching off of the door by means of crowbars or wedges. In an ordinary safe the massive bolts, three or more in number, shoot only at the front, and fixed dogs or sham bolts fit into slots at the back or hinged side. This arrangement is sufficient to keep the door closed independent of hinges, which are merely the pivot on which the door turns. In all Chubb's safes bolts shoot both to front and back; and in the higher quality of that and of every other good maker bolts shoot on every side,—front, back, top, and bottom. Ordinarily the bolts shoot straight into the slot as in an ordinary lock; but, to defy wrenching, additional grip is secured by Chatwood, who makes a bolt with a clutch or projection, which falls into a recess in the slot and thus holds against any direct wrench. In Chubb's finer safes the bolts shoot diagonally all round, so that in each face of the door they go in two different directions. Safe bolts are shot not by the key, as in an ordinary lock, but by the door handle, and the key simply secures them in their position. By this arrangement, patented by Mr Charles Chubb in 1835, a series of the most ponderous bolts can be secured in locked position by a small key which can be carried in the vest pocket. The lock of a safe must be a careful piece of mechanism, not subject to derangement, unpickable, and gunpowder-proof. The portion of the door on which it is fastened is generally provided with extra precautions against drilling. A safe being well made and securely locked remains vulnerable through the medium of the key, which may be surreptitiously obtained either for direct use or to form a mould by which false keys can be cut. On this account, keyless locks and time locks are coming into great favour in America. In keyless permutation locks, such as those of Hall, Sargent, Yale, and Dalton, the bolts can be withdrawn only after an indicator has been successively set against a combination of numbers arranged before the closing of the door ; and in the time lock of these inventors the safe can only be opened at any hour to which the time controller is set before closing. Electrical arrangements have also been attached to safes by which signals are conveyed to any spot when a safe so guarded is unlawfully interfered with.

It is much easier to render a safe fire-proof than to guard it against burglary. It requires nothing more than a calculation of the intensity and duration of any fire to which it is likely to be exposed, and the provision of a sufficient lining of fire-resisting material. What is princi-pally used is a mixture of some absorbent medium—such as sawdust, powdered gypsum or cement, or infusorial earth—with ground alum. Asbestos, silicate cotton, mica, and other non-conductors are also used; and by some leakers sealed tubes of alkaline salts are distributed through the absorbent material. These burst when exposed to high heat and their contents saturate the surrounding substance A carefully packed shell of not less than 3|-inches of tii°. fire-resisting medium should line the interior of every fire-proof safe; but in many cheap safes a quantity of brick dust is the only fire-resisting medium.

Where an ordinaly safe provides insufficient accommoda-tion the strong room takes its place. Such an apartment, being generally in the basement of a building, presents no special difficulties to make it proof against fire and thieves. Thickness of walls, built by preference of hard brick laid in cement, and liberal use of cement within the walls, as well as at the floor and over the arched roof, give strength against both fire and burglars. The interior of a strong room is generally lined with boiler-plate, and, in addition to the massive steel and iron door, it has an inner wrought-iron grill-door, which secures the vault during business hours and permits the ventilation of the apartment. Within such a strong room extra strong chambers or separate safes may be placed, and in this way precautions may be indefinitely multiplied.

The most complete examples of safe and strong-room arrange- ments are afforded by the public safes or safe-deposits erected in most of the great cities of America and in London. The premises of the National Safe Deposit Company in London consist of a large isolated building in Queen Victoria Street. The building, which is fire-proof, covers and surrounds the great safe vault or citadel, which is sunk in the ground to a depth of 45 feet. The vault itself, founded on a bed of concrete 20 feet in thickness, has walls, 3 feet thick, of hard blue brick laid in cement, with an external lining of fire-brick, and is lined internally with cast-iron plates 4| inches thick chilled on one side, the plates having embedded in them a network of strong interlaced wrought-iron bars. The vault is divided into four tiers or stories with eight sepai'ate compart- ments in each, which, after business hours, are closed with doors raised and lowered by hydraulic power. These doors, which each weigh four tons, are built up, 12 inches thick, of combinations of hard and tough metal to resist fracture and drilling, and when they are raised for business purposes the entrance to each compartment is protected by a massive wrought-iron grill. Within the thirty- two compartments there is space for about 20,000 safes of various sizes, which are let to owners of valuables, each renter having the sole control of the safe hired by him. Additional security is obtained by the patrol of armed watchmen, and generally it may be said that in the institution precautions have been carried almost to the pitch of perfection, if indeed they have not been pushed to needless excess. (J. PA.)

The above article was written by: James Paton, Curator, Corporation Galleries of Art, Glasgow,

Search the Encyclopedia:

About this EncyclopediaTop ContributorsAll ContributorsToday in History
Terms of UsePrivacyContact Us

© 2005-17 1902 Encyclopedia. All Rights Reserved.

This website is the free online Encyclopedia Britannica (9th Edition and 10th Edition) with added expert translations and commentaries