A simple fastening to doors. The original and simplest form of a latch, is the little falling bar hooked, and the catch; the former being fixed on the door, and dropping into a notch of the latter, which is fixed to the door-post. On the opposite side of the door such latches were formerly lifted by a string passing through the door, or by a finger inserted through a hole under the latch. In process of time a little lever was made to perform this office, and next to the lever was added a bowed handle. This very useful combination now goes by the name of a thumb latch, and such are our facilities of manufacture, that millions of these are made annually in the neighbourhood of Birmingham, and rendered to the dealers at prices averaging not more than three half-pence each. The work people, are, however, very inadequately remunerated for their valuable labour. Thumb latches of a more massive and finished description, with round black varnished handles, are distinguished from the former by the term of Norfolk latches.
For the inner doors of houses a variety of spring latches are extensively used termed bow latches, (which are those on square plates with brass knob or ring handles,) and long latches (chiefly distinguished from the other by the length and form of their plates). Some of these are made without handles, and keys are employed to open them externally; but wherever elegance or neatness is studied, mortise latches are used; these are let into the thickness of the door in the manner of mortise locks, and nothing is visible on either side of the door but an ornamental handle; the folding windows called French sashes are usually provided with them. There is another kind of latch which affords all the security of a lock, with numerous wards, termed the French latch. A small, hut broad, flat key, having numerous wards cut out of a solid plate of metal, is passed through a narrow horizontal perforation in the door (covered with a suitable escutcheon), whence it enters the body of the latch; the key being then merely lifted upwards, the solid wards of the latch pass through the interstices of the key, permitting the latter thus to unlatch the door.
A very simple and convenient common latch, well adapted to stable doors, was recently invented by Mr.T. N. Parker, of Sweeny, which we will take leave to call the pull latch, as it may be opened on either side of the door by a pull. It is represented in the cut on the following page; a a is a curved piece of iron like the letter S, which turns upon a joint at b, and passes through a hole in the door at c, and supports the latch d, which is inclosed by the usual keeper e. On one side of the door the curved hook a acts as a lever of the first class in lifting the latch; while in the other the curved hook a acts as a lever of the second class for the same purpose. The common lever is thus converted into two hndles besides performing its own office.