- ]90 ON THE USE OF BRONZE CELTS
this iiiacliiiie. It is that variety which was worked with a bow. We observe, first, a block ot" wood containing a pivot for the instrument to turn upon ; then a wooden frame con- taining two long parallel staves, round both of which the string of the bow passes. Into the end of this frame is fixed a kind of weapon like a javelin. This, together with the frame, slants upwards and is directed to the mortar which lies between two courses of stone. The three concentric circles are a rude representation of the cloud of dust formed by the revolution of the drill. The whole of this machine might be very easily con- structed whenever it was wanted ; and for a metallic point, it is probable that the soldiers sometimes had recourse to the stronger and heavier varieties of spear-heads, especially to those of a quadrate form, such as would be cast in two of the sides of the stone celt-mould represented and described in the last section. But we may also suppose that strong pointed instruments, more especially adapted to perforate walls, were cast for this express purpose, and on this [)rinciple we may perhaps ex})lain the use of some articles of bronze, wdiicli are found and classed with celts, but to which no particular destination has hitherto been assigned. Of such objects I produce two examples. One is the instrument found at Peel in the Isle of Man, which is represented in the ArcJiaenlogical Journal^ vol. ii.. p. 187, and repeated in the annexed wood-cut, It seems most exactly adapted to the purpose which I have sup- posed. Instead of the two edges of an ordinary spear- head, we see here four planes each with two edges, so that as the' machine was turned backwards and forwards by the bow, four edges would rasp the brick, stone, or mortar in turning in one direction, and the four alternate edges would do the same in turning in the other direction. The (toinminuted materials of the wall would fall in powder thioiigli the four channels which separate the cutting edges. The instrument has a socket and loops for fastening it to
