142 LODE 



front or foremost of the range of six tumblers, each of which has the usual slot and 

 notches. In other tumbler-locks the stump or stud which moves along these slots is 

 riveted to the bolt, in such manner that, if any pressure be applied in an attempt to 

 withdraw the bolt, the stump becomes pressed against the edges of the tumblers, and 

 bites or binds against them. How far their biting facilitates the picking of a lock 

 will bo shown further on ; but it will suffice here to say, that the moveable action given 

 to the stump in the Hobbs lock transfers the pressure to another quarter. The stump 

 s is riveted to a peculiarly-shaped piece of metal h p (fig. 1400), the hole in the centre 

 of which fits upon a centre or pin in a recess formed at the back of the bolt ; the 

 piece moves easily on its centre, but is prevented from so doing spontaneously by a 

 small binding spring. The mode in which this small moveable piece takes part in tho 

 action of the lock is as follows : when the proper key is applied in the usual way, the 

 tumblers are all raised to the proper heights for allowing the stump to pass hori- 

 zontally through the grating ; but should there be an attempt made, either by a false 

 key or by any other instrument, to withdraw the bolt before the tumblers are pro- 

 perly raised, the stump becomes an obstacle. Meeting with an obstruction to its 

 passage, the stump turns the piece to which it is attached on its centre, and moves the 

 arm of the piece p so that it shall come into contact with a stud riveted into the case 

 of the lock; and in this position there is a firm resistance against the withdrawal of 

 the bolt. The tumblers are at the same moment released from the pressure of the 

 stump. There is a dog or lever d, which catches into the top of tho bolt, and 

 thereby serves as an additional security against its being forced back. At k is tho 

 drill-pin on which the pipe of the key works ; and r is a metal piece on which the 

 tumblers rest when the key is not operating upon them. - 



Another lock, patented by Mr. Hobbs in 1852, has for its object the absolute 

 closing of the key-hole during the process of locking. The key does not work or 

 turn on its own centre, but occupies a small cell or chamber in a revolving cylinder, 

 which is turned by a fixed handle. The bit of the moveable key is entirely separable 

 from the shaft or stem, into which it is screwed, and may be detached by turning 

 round a small milled headed thumb-screw. The key is placed in tho key-hole in 

 the usual way, but it cannot turn ; its circular movement round the stem as an axis 

 is prevented by the internal mechanism of the lock ; it is left in the key-hole, and 

 the stem is detached from it by unscrewing. By turning the handle, the key-bit, 

 which is left in the chamber of the cylinder, is brought into contact with the Avorks 

 of the lock, so as to shoot and withdraw the bolt. This revolution may take place 

 whether the bit of the moveable key occupy its little cell in tho plate or not ; only 

 with this difference that if the bit be not in the lock, the plate revolves without 

 acting upon any of the tumblers ; but if the bit be in its place, it raises the tumblers 

 in the proper way for shooting or withdrawing the bolt. It will be understood that 

 there is only one key-hole, namely, that through which the divisible key is in- 

 serted ; the other handle or fixed key working through a hole in the cover of the 

 lock only just large enough to receive it, and not being removable from the lock. 

 As soon as the plate turns round so far as to enable the key-bit to act upon the 

 tumblers, the key-hole becomes entirely closed by the plate itself, so that the actual 

 locking is effected at the very time when all access to the interior through the key- 

 hole is cut off. When the bolt has been shot, the plate comes round to its original 

 position, it uncovers the key-hole, and exhibits the key-bit occupying tho little cell 

 into which it had been dropped; the stem is then to be screwed into the bit, and the 

 latter withdrawn. It is one consequence of this arrangement, that the key has to be 

 screwed and unscrewed when used; but through this arrangement the key-hole 

 becomes a sealed book to one who has not the right key. Nothing can be moved, 

 provided the bit and stem of the key be both left in ; but by leaving in the lock the 

 former without the latter, the plate can rotate, the tumblers can be lifted, and the 

 bolt can be shot. 



LOCUST TREE. A North American tree, tho Robinia pscudacacia. ' It grows 

 most abundantly in the southern States ; but it is pretty generally diffused through 

 the whole country. It sometimes exceeds four feet in diameter and seventy feet in 

 height. The locust is one of tho very few trees planted by tho Americans.' This 

 wood is much used for ships' tree-nails, and is employed for stakes and pales. 



The wood of tho Hymentea Courbaril is also known as locust wood. 



iODF, (a mining term). A mineral lode, or a mineral vein, is the name given to 

 a fissure in the crust of the earth which has been filled in with metalliferous matter. 

 Tho miner gives the same name lode to a fissure filled with quartz, carbonate of lime, 

 &c - , but then ho says the lode is not ' mineralised,' confining the word ' mineral ' to 

 metalliferous matter. 



Tho term vein has frequently led to tho idea that it expresses tho condition of 

 something analogous to the blood-vessels of the animal body, to which a lode has not 



