From D. Bard
John Galbraith’s new screw with triangular hole may well be too late (Technology, 3 December and Letters, 24/31 December). In Canada there is already in hardware shops a screw with a square hole which must share many of the advantages, and screwdrivers with a tapering square end to fit it are available.
I can confirm that the tapering fit does provide a very secure grip, and of course there is no danger of slipping out of the slot, as one does with conventionally slotted heads, or raising a sharp splinter of metal to injure the next handler.
There does seem to be a communication gap across the Atlantic: another excellent North American idea virtually unobtainable in Britain is the spirally fluted ordinary nail (I know the hardened version can be bought here) which gives, at a guess, ten times the grip of an English wire nail. I always restock when I visit Canada.
