A Mudlark is someone who scavenges in river mud for items of value, especially in London during the Industrial Revolution. Poor peasants would scavenge in the River Thames during low tide, searching for anything of value.
During the Industrial Revolution, mudlarks were usually young children or widowed women. Becoming a mudlark was a cry of desperation as it is considered one of the worst "jobs" in history. At the time of the Industrial Revolution, excrement and waste would wash onto the shores from the raw sewage which wasn't treated. The corpses of humans, cats and dogs would also wash up. Mudlarks would be lucky if they made a penny a day selling what they had found during low tide, which was the only time people could scavenge along the shores of the rivers.
The word was used in the late 18th century as a slang expression both for a pig, and for one of the scavengers on the Thames.
Frederick Marryat in his 1840 novel Poor Jack, describes the fictional rise of a mudlark, Thomas Saunders, to the position of river pilot. Saunders, a sailor's son, having been abused and neglected by his mother, turns at an early age to life on the waterfront:
Indeed, I was now what is termed a regular Mud-larker, picking up halfpence by running into the water, offering my ragged arm to people getting out of wherries, always saluting them with "You haven't got never a halfpenny for poor Jack, your honour?" and sometimes I did get a halfpenny, sometimes a shove, according to the temper of those whom I addressed.
The same source describes mudlarks trying to scrounge pennies off parties visiting inns and taverns on the waterfront to enjoy the whitebait:
Sometimes they would throw a sixpence into the river, where the water was about two feet deep, to make us wet ourselves through in groping for it. Indeed, they were very generous when they wished to be amused; and every kind of offer was made to them which we thought suited to their tastes, or likely to extract money from their pockets. "Dip my head in the mud for sixpence, sir!" one of us would cry out; and then he would be outbid by another.
"Roll myself all over and over in the mud, face and all, sir - only give me sixpence!"
In addition to earning coppers this way however Saunders also scavenges bits of rope, oakum and driftwood and sells them. As he grows up, he becomes aware of other less honest but more profitable ways of earning a living on the river:
I have said in a former chapter that I was a regular mudlarker. So I was, as far as the ostensible occupation of those who are so denominated went - to wit, "picking up pieces of old rope, wood, etc." But the mudlarkers, properly speaking, at that time composed a very extensive body on the river, and were a more humble portion of the numerous river depredators of which I may hereafter speak. A mudlarker was a man who had an old boat, generally sold by some merchant vessel, furnished with an iron bar full of hooks, which was lowered down by a rope to catch pieces of cordage, oakum, canvas or other articles which might fall overboard...But, as I observed, this was the ostensible mode of livelihood; they had other resources, to which I shall presently refer.
Marryat goes on to describe one mudlarker taking his boat out, apparently to dredge for floating junk, but really to receive stolen items off the merchant ships, convey them ashore and fence them. Henry Mayhew in his book, London Labour and the London Poor; Extra Volume 1851 provides this detailed description of mudlarks:
THEY generally consist of boys and girls, varying in age from eight to fourteen or fifteen; with some persons of more advanced years. For the most part they are ragged, and in a very filthy state, and are a peculiar class, confined to the river. The parents of many of them are coalwhippers--Irish cockneys--employed getting coals out of the ships, and their mothers frequently sell fruit in the street. Their practice is to get between the barges, and one of them lifting the other up will knock lumps of coal into the mud, which they pick up afterwards; or if a barge is ladened with iron, one will get into it and throw iron out to the other, and watch an opportunity to carry away the plunder in bags to the nearest marine-storeshop.
They sell the coals among the lowest class of people for a few halfpence. The police make numerous detections of these offences. Some of the mudlarks receive a short term of imprisonment, from three weeks to a month, and others two months with three years in a reformatory. Some of them are old women of the lowest grade, from fifty to sixty, who occasionally wade in the mud up to the knees. One of them may be seen beside the Thames Policeoffice, Wapping, picking up coals in the bed of the river, who appears to be about sixtyfive years of age. She is a robust woman, dressed in an old cotton gown, with an old straw bonnet tied round with a handkerchief, and wanders about without shoes and stockings. This person has never been in custody. She may often be seen walking through the streets in the neighbourhood with a bag of coals on her head.
In the neighbourhood of Blackfriars Bridge clusters of mudlarks of various ages may be seen from ten to fifty years, young girls and old women, as well as boys.