author writes : ' At the siege of Rhodes in 1480, the Turks set up a battery of sixteen great cannon, but the Christians successfully opposed the cannon with a counter-battery of new invention.¹

'An engineer, aided by the most skilful carpenters in the besieged town, made an engine that cast pieces of stone of a terrible size. The execution wrought by this engine prevented the enemy from pushing forward the work of their approaches, destroyed their breastworks, discovered their mines and filled with carnage the troops that came within range of it.'

At the siege of Mexico by Cortes in 1521, when the ammunition for the Spanish cannon ran short, a soldier with a knowledge of engineering undertook to make a trebuchet that would cause the town to surrender. A huge engine was constructed, but on its first trial the rock with which it was charged instead of flying into the town, ascended straight upwards and falling back to its starting-point destroyed the mechanism of the machine itself.²

Though all the projectile engines worked by cords and weights disappeared from warfare when cannon came to the front in a more or less improved form, catapults—if Vincent le Blanc is to be credited—survived in barbaric nations long after they were discarded in Europe.

This author (in his travels in Abyssinia) writes 'that in 1576 the Negus besieged Tamar a strong town defended by high walls, and that the besieged had engines composed of great pieces of wood which were wound up by cords and screwed wheels and which unwound with a force that would shatter a vessel, this being the cause why the Negus did not assault the town after he had dug a trench round it.³

¹ Called a new invention because the old siege engine of which this one (probably a trebuchet) was a reproduction had previously been laid aside for many years.

² Conquest of Mexico. W. Prescott, 1843.

³ Vincent le Blanc, Voyages aux quatre parties du monde, redige par Bergeron, Paris, 1649. Though the accounts given by this author of his travels are imaginative, I consider his allusion to the siege engine to be trustworthy, as he was not likely to invent so correct a description of a catapult.

Fig. 185. - Criticism. - A stonebow of vast size. A and B represent two kinds of lock. In A, the catch of the lock over which the loop of the bow-string was hitched, was released by striking down the knob to be seen below the mallet. In B, the catch was set free by means of a lever. C, shows the manner of pulling back the bow-string. By turning the spoked wheels, the screw-worm revolved the screwed bar on which the lock A, travelled. The lock, as may be seen, worked to or fro in a slot along the stock of the engine. In the illustration the bow is fully bent and the man indicated is about to discharge the engine. After this was done, the lock was wound back along the screw-bar and the bow-string was hitched over the catch of the lock preparatory to bending the bow again.

Besides being a famous painter, Leonardo was distinguished as an inventor of and exact writer on mechanics and hydraulics.

' No artist before his time ever had such comprehensive talents such profound skill or so discerning a judgment to explore the depths of every art or science to which he applied himself.' JOHN GOULD, Dictionary of Painters, 1839.

From the above eulogy we may conclude that the drawings of ancient siege engines by Leonardo da Vinci are fairly correct.