We must not forget its extreme usefulness for transmitting sketches. A very simple diagram often explains a thing better than pages of letter-press. The telautograph may help in the detection of criminals, a pictorial presentment of whom can by its means be despatched all over the country in a very short time. And in warfare an instrument flashing back from the advance-guard plans of the country and of the enemy’s positions might on occasion prove of the greatest importance. MODERN ARTILLERY. The vast subject of artillery in its modern form, including under this head for convenience’ sake not only heavy ordnance but machine-guns and small-arms, can of necessity only be dealt with most briefly in this chapter. It may therefore be well to take a general survey and to define beforehand any words or phrases which are used technically in describing the various operations. The employment of firearms dates from a long-distant past, and it is interesting to note that many an improvement introduced during the last century is but the revival of a former invention which only lack of accuracy in tools and appliances had hitherto prevented from being brought into practical usage. So far back as 1498 the art of _rifling_ cannon in straight grooves was known, and a British patent was taken out in 1635 by Rotsipan. The grooves were first made spiral or screwed by Koster of Birmingham about 1620. Berlin possesses a rifled cannon with thirteen grooves dated 1664. But the first recorded uses of such weapons in actual warfare was during Louis Napoleon’s Italian campaign in 1859, and two years later by General James of the United States Army. The system of _breech-loading_, again, is as old as the sixteenth century, and we find a British patent of 1741; while the first United States patent was given in 1811 for a flint-lock weapon. _Magazine_ guns of American production appeared in 1849 and 1860, but these were really an adaptation of the old matchlock revolvers, said to belong to the period 1480-1500. There is one in the Tower of London credited to the fifteenth century, and a British patent of 1718 describes a well-constructed revolver carried on a tripod and of the dimensions of a modern machine-gun. The inventor gravely explains that he has provided round chambers for round bullets to shoot Christians, and square chambers with square missiles for use against the Turks! The word “ordnance” is applied to heavy guns of all kinds, and includes guns mounted on fortresses, naval guns, siege artillery, and that for use in the field. These guns are all mounted on stands or carriages, and may be divided into three classes:-- (i.) _Cannon_, or heavy guns. (ii.) _Howitzers_, for field, mountain, or siege use, which are lighter and shorter than cannon, and designed to throw hollow projectiles with comparatively small charges. (iii.) _Mortars_, for throwing shells at a great elevation.