Q From Pete Brown: I have always understood a lead-swinger to be a slacker, someone who feigns illness or injury to avoid working. A bit of cursory research unearthed a definition that described it as a World War I army phrase referring to the taking of a sounding to determine the depth of water, which was apparently an easy task. This doesn’t quite ring true in my mind: first, this depth-sounding technique is much, much older than World War I; second, I know military slang transfers fairly freely between different branches of the service, but how or why would this nautical practice come to be associated with a land army instead of a navy? Any insights would be most welcome.
A The expression does seem extremely puzzling, but it is possible to rationalise the maritime and army usages. To fill in the blanks we need to go into the background a bit more. Aficionados of Captains Aubrey and Hornblower can skip the next paragraph.
At sea, the lead was a literal lump of lead weighing nine pounds (four kilos) fixed to a long line, usually with tallow on the bottom. The leadsman cast the lead over the side to establish the depth of water (there were coded markers fixed to the line so that he could determine the depth in the dark). The tallow brought up a small sample of the sea bottom, which would give an experienced navigator who knew the coast more details about where the ship was. The job of the leadsman was both skilled and arduous. The safety of the ship often depended on him, since the only time he was needed was in shallow water in which there was a risk of grounding. He was working under the eye of the officers all the time, often soaked to the skin because he had to be at the ship’s side no matter what the weather. The wet line and heavy weight made it hard work to cast and pull up the lead each time, and the action had to be repeated at frequent intervals.
As you say, none of this fits with the idea of swinging the lead as a term for idleness or malingering — quite the reverse. You have found why so many writers on word histories are puzzled by the slang phrase. The article you read is surely wrong to suggest that the army usage ever literally referred to depth-sounding, though it was right to say that the term arose in the military early in the twentieth century. It may have been a typical landlubberly misunderstanding of the job of the leadsman, seen by soldiers as something easy rather than the hard task it really was.
On the other hand, a number of subscribers wrote following the first appearance of this piece, to say that there may be a direct link with sailors taking depth soundings. It seems that, because it was such arduous work, lazy sailors who were not being directly supervised would pretend to cast the lead by just swinging it — hence the expression. I can’t prove its veracity, and the fact that it appeared so late in the history of the sea and not among mariners themselves, makes me a little wary of it, but it does make sense.
As a side-note, Eric Partridge, in his Dictionary of Slang and Unconventional English, says that there was an earlier military slang term to swing the leg, with the same sense, which was converted by folk etymology into swing the lead. I’ve not been able to confirm the existence of this older term, but it would help to explain how a nautical term came into army use.