LOCKS 



139 



square feet 

 . 300 

 . 240 

 . 200 

 . 170 

 . 150 



IiOADSTONE, Magnetic Iron-stone. (Fer oxyduU, Fr. ; Magneteiscnsteln, 

 Ger.) An iron ore, consisting of the protoxide and peroxide of iron in a state of 

 combination. 



It was first discovered in Magnesia, and from that province has been derived the 

 name MAGNET applied to this ore of iron. The term loadstone, however, is given to 

 those specimens which are powerfully magnetic only. See IKON. 



XiOAIME. (Terre limoneuse, Fr. ; Lehm, Ger.) A native clay, mixed with quartz- 

 sand and iron-ochre, and occasionally with some carbonate of lime. 



' More commonly we find sand and clay, or clay and marl, intermixed in the same 

 mass. When .the sand and clay are each in considerable quantities, the mixture is 

 called " loam." ' Lycll. 



LOCKS. Although locks are distinctly a manufacture, yet they wore not embraced 

 in the early editions of this work ; the chief cause of this being the desire on the part 

 of Dr. Ure to limit the articles of the Dictionary to such manufactures as were not 

 comprehended within his meaning of the term Handicraft. 



The lock manufacture is essentially one of handicraft ; and seeing that these 

 volumes could not possibly enter into any detailed description of this and numerous 

 other trades, as watch-making and the like, it has been determined that a brief notice 

 of the several kinds of locks alone shall find a place in its pages. 



The lock manufacture of this country is confined almost exclusively to Wolver- 

 hampton and the neighbouring village of Willenhall. There are very few large 

 manufactories, almost all kinds of locks being made by small masters, employing 

 from half-a-dozen to a dozen men. 



In nearly every kind of lock a bolt shoots out from the box or lock, usually of an 

 oblong shape, and catches in some kind of staple or box fixed to receive it. In some 

 a staple enters the lock, and the bolt passes through the staple within the lock. The 

 lock of a room-door is of the first character ; the lock of a writing-desk, or ordinary 

 box, is of the second kind. The key is merely a bent piece of iron, which, on entering 

 the lock, can move freely, and push forward the bolt. To the bolts of superior locks 

 springs are attached, and the force required to turn the key in a lock is the force 

 necessary to overcome the resistance of the springs. The following two figures, 1397, 

 1398, represent the character of a lock with wards or wheels, which are introduced to 

 give safety. Fig. 1397 is an ordinary back-spring lock, representing the bolt half- 

 shot ; a' a" are notches on the iinder side of the bolt, connected by a curved portion ; 

 b is the back-spring, which is of course compressed as the curved portion of the bolt 



1397 



1398 



passes through the aperture prepared for it in the rim of the lock ; when the bolt is 

 withdrawn, the notch a' rests in the rim ; when the bolt is shot, the notch a" rests in 

 the same manner. The action of the key and wards is shown in fig. 1398. The 

 curved pieces of metal are the wards ; and there are two clefts in the bit of the key 

 to enable it to move without interruption. 



The tumbler-lock is shown in its most simple form in jig. 1399. Hero the bolt has 

 two slots, a a, in the upper part ; and behind the bolt is a kind of latch, b, which 

 carries a projecting piece of metal ; c, this is the tumbler, which moves freely on 

 a pivot at the other end. When the bolt is fully shot the projecting piece of metal 

 falls into one notch, and when withdrawn it falls into the other. It will bo evident 



