Before the gunner could get to what Kipling called the never-ending mystery of his art, he had to finish his basic training. We looked at some — but not all — field artillery training back in August, but that was just the beginning. The artillery recruit’s syllabus also included nineteen hours of “cordage, knotting, &c.”
Cordage means ropes, whether of fibre or wire. In the Field Service Pocket Manual, we begin with their size and strength. “The size of a rope is denoted by its circumference in inches, and its length is given in fathoms. (A fathom is 6 feet.)”
So far so good. The next point is fairly comprehensible too: “For field purposes, the safe working load for all cordage has been laid down as C2 cwts [hundredweights], while for steel wire rope it may be taken as 9 C2 cwts, where C is the circumference in inches. Steel wire rope may be taken as twice as strong as iron wire rope.” A hemp or sisal rope with a three-inch circumference can safely be loaded with 9 hundredweights. Of course, a hundredweight in British reckoning is not 100 pounds, but 112 pounds, but that’s not a problem. An American not understanding that would only under- not over-, estimate, the safe working load of his rope.
The third point is also not too arcane: “The strength of wire varies greatly; as a very rough rule it may be taken that the breaking weight in pounds equals three times the weight per mile in pounds. Steel wire may be taken as about twice as strong.” Unfortunately, the manual does not tell us where to find out a wire’s weight per mile in pounds.At this point, we call in the engineers, who have these facts at their fingertips — or at least in readily available tables:
By point four, I understand why this information is in the Field Service Pocket Manual – no one is expected to remember it – they just have to know where to look it up:
“The strength of a lashing round two objects may be taken as four-fifths of the number of times the lashing passes from one object to the other multiplied by the unit strength of the lashing, e.g., a square lashing with four turns has a holding power of 4/5 x 16 x strength of lashing.”
It is, of course, officers who are responsible for deciding if a trestle or the rope used in slinging horses or guns on or off transport was adequate for the job.
Quotations are from the Field Service Pocket Book. HMSO. 1914.109.
The image of a trestle is from page 111 of the same source.
Copyright 2016. See “More about this project.”