Camden states that at the siege of Bedford Castle by King John one of the mangonels, _i.e._ trebuchets, threw millstones into the castle. He mentions seven great machines being at work at one time. Again, when Henry III. besieged Kenilworth, in 1266, stones of extraordinary size were used as missiles; some are still preserved at the Castle and two are at the Rotunda, Woolwich, the diameters being 18-1/2 inches and 16-1/4 inches; the weight 256 lbs. and 165 lbs. respectively. At Pevensey Castle catapult stone shot of 144, 156, and 241 lbs. respectively have been discovered. The great trebuchet constructed by Edward I. for the siege of Stirling Castle cast balls weighing between two and three hundredweight. The several parts of this great machine were sent by sea, but the Castle surrendered before its efficacy could be tried. The King was annoyed that this, his pet device, the "War-Wolf," as it was termed, had not had an opportunity, and therefore ordered the garrison to remain within while he took a few "pot-shots" at their defences. Such projectiles would almost demolish a house, and were nearly as formidable as modern shells; their great weight would batter every portion of a medieval castle except the very thickest of walls. The platforms of earth thrown up by besiegers to sustain their great engines remain in many places intact to-day; thus round Berkhampstead Castle are eight, upon which the trebuchets of the Dauphin were erected in 1216, when he battered the castle into submission in about a fortnight. The terms mangonel, petrary, balista, onager, scorpion, perrier, catapult, etc., when used by historians of the middle ages, generally apply to the trebuchet and its varieties, large and small. _The Arblast, Espringale, and Spurgardon_ were engines based upon the cross-bow or tension principle; some were of considerable size and threw huge bolts tipped with iron. Another and a common use was to convey ignited incendiary matter into the enemy's quarters by their means. They were mounted upon towers, curtain walls, and in the baileys, while in the open when placed upon wheels they served the purpose of field-pieces. [Illustration: RAISING THE PORTCULLIS.] _The Ram_, based upon the weapon used by the ancients, was in frequent use. The working parts and the men manipulating it were protected by a pent-house called the "Snail," or "Whelk," having a roof of considerable thickness. In this house it was suspended by chains and pulled backwards and forwards by hand or mechanical appliances; when released, it smashed the stones in the wall to powder, so that they could be subsequently removed from the defences. To mitigate the effects the besieged let down mattresses, bags of wool, and coiled rope mats by chains from the ramparts.