Frequently a key has opened a lever lock for years, and suddenly fails to do so; this is generally due to the key being too worn to engage properly any longer, and nearly always it will be found that the portion that engages with the bolt is the worn part. Inspection will show whether all its edges are much rounded off, denoting wear; if so a temporary remedy will be effected by placing the key upon a metal block, and with a light hammer flattening out the worn part so that it tends to resume its former length of reach from the key stem. This will give the key a new lease of life, but a new one will be required at some later period. It does not follow that because a key has the appearance of a lever key, that the lock is a lever lock; it is perfectly simple to leave out all the lever work in such a lock, and leave the bolt in only. In fitting a key to a lever lock the best way to proceed is to open the lock, inspect the interior for any defects, and proceed to make the key operate each part in turn. Take out all the lever action, keeping each in its correct order, and file the key to operate the bolt only. Then put back the first lever work, and file the key to suit and so on. If it be found that any undesired person has a key to open a certain lock, and it be wished to prevent this, then open the lock and alter the position or order of the lever parts. File a new key to fit the rearranged lock, close and reattach the lock to the door, etc. The original key will now not open the lock, and this has been attained without going to the cost of a new lock. In the Yale type of lock, the key has to rotate a cylinder into which it is inserted. The opening into this cylinder for the key has a peculiar shape, characteristic of Yale locks, and any Yale key will enter a Yale lock, but will not turn it unless designed for it. It will be noted that the top edge of a Yale key has a waved outline. The rotation of the above mentioned cylinder is prevented normally by a number of small steel cylinders or pegs, which project downwards into the cylinder, through holes provided, and under the action of small springs. In these small holes in the main cylinder are other small pegs, against the lower ends of which the key bears when passed into the cylinder or lock. All these small pegs, etc., are of various lengths, and when the key is used, the form and height of the key edge, together with the length of the pegs in the cylinder brings the top of these pegs exactly flush with the outside surface of the main cylinder. The pegs which dropt down into the cylinder from the outside, prevented the cylinder from rotating, but when the key, by means of its edge, forces the pegs to be flush with cylinder surface, then the cylinder is freed from the holding action of the outside pegs, and so can be rotated and the lock opened. Now since, as stated above, the pegs are of different lengths, it follows that very many different variations oi key edge shape can be required for different arrangements of these pegs. In making a duplicate key for these locks, it is sufficient to clamp them together in a vice, with the bottom edges level and file the new key blank to be exactly duplicate of the original key. Should a key, through wear, fail to open the lock, it is difficult to tell by inspection just which part is defective, and by far the better way is to take the lock to pieces and adjust the key to it. Take the lock bodily out of the door, note the small screw and plate at the end of the main cylinder remote from the key hole, remove them, and holding the lock upright as it appears when in use, push a tube or rod against the end of the cylinder and force it slowly out. This circular tube or rod must be a fairly good fit in the hole in which the cylinder rotated, so that it absolutely prevents the pegs and springs in the lock body from coming out; keep the rod there while you proceed with the cylinder. Keep this cylinder right way up and note that the top centre line has a number of small circular holes in it, in each of which is seated a steel peg. These pegs, when the key is not in the lock, are sunk below the edge of the cylinder, and so allow the pegs in the lock body to be shot into these holes, and so lock the cylinder. Now slide the key gently on to the cylinder (still holding it with the holes on top), and observe that the action of the waved top edge of the key brings the tops of the small pegs flush with the surface of the cylinder. If the key is worn, then this worn place will betray itself by being unable to force the peg concerned into a position flush with the cylinder surface, but will lie below it. The key edge must be raised in order to raise this peg ; this can be done by either tapping out the edge, with a light hammer and block, or else increasing its height by use of some hard solder; both methods will give good results, and will require trimming to correct height with a fine file. A new key blank can be fitted in the same way, filing the portion of the key concerned with each peg, one at a time. If it be desired to alter the shape of the operating key for any lock, for any reason, then the positions of the pegs in the cylinder are changed about, just anyhow, and a new key filed to suit. Note that the position or arrangement of the pegs in the lock body need not be altered ; their duty is simply to drop into the holes that are exposed in the cylinder surface when the key is withdrawn. Above all, great care must be taken not to let the pegs and springs escape from the lock body, as their recovery from the bench or floor, and insertion into place again, is a tedious business; proper use of the tube, rod, or plug as described above quite prevents this happening. When inserting the cylinder into the lock again, take great care that the rod or plug, etc., be pushed out by the cylinder end when inserting it, and keep these ends in contact until the cylinder is right home, then put back the securing plate and screw at once. It will be seen that these locks do not permit easy opening except by the correct key, also that very many different keys can be made necessary for locks using different arrangements of a reasonable number of indifferent standard-length pegs in the cylinder. The shape of the key entry hole also provides an additional safeguard. Of course, given the opportunity of making a noise or causing damage, or both, these locks can be forced, but this is very different to being quietly " picked," an operation that can be easily performed on most " ward " locks. There are many inexpensive locks and padlocks that depend entirely upon the peculiar shape of the key body section for the value of the lock, as no key unless within the certain limits of the particular section can enter the lock. Their protective value depends upon the skill of, and the tools available by, any person wishing to open them ; generally given a few odds and ends of wire, and pieces of sheet metal, a locksmith would open any in (puck time. This combination not being always available, they are generally forced or broken open or left alone. Speaking generally, lock makers now can produce a lock that cannot be picked in the time at the usual disposal of a burglar; but they cannot of course produce commercially a lock that cannot be picked, provided unlimited time, tools, and skill are available, and indeed there is no need or call for such a lock. If such locks were made and sold at a commercial price, the only result would be that the receptacles to which they were fitted would be attacked, instead of the lock. If faced with a locked drawer, box or door, etc., which for some reason cannot be unlocked, and it be desired to force it without causing too much damage to the woodwork, proceed as follows : By means of wedges, either wood or metal, force the two edges, etc., apart so that the bolt of the lock can be got at. Insert the end of a small crowbar or the end of a large screwdriver between the end of the lock bolt and the woodwork, and endeavour to force the bolt down into the lock. If this cannot be effected, then the best thing to do is to place a blunt steel chisel (not a wood workers' chisel) against the flat side of the exposed bolt, and with a hammer drive the lock bodily out of the woodwork. Generally the damage to the lock, or the woodwork is only slight, and easily repaired, and also should not be visible from the outside. Should the reader have a lock, or key repair job waiting, but happens to be not conversant with lock work, it is strongly suggested that he finds an old ward, also a lever lock, opens them, and examines thoroughly the method of working.

See also Vol. HI., page II.