By upgrading the original arrowhead harpoon with a locking toggle device, Lewis Temple, an African-American inventor, created "Temple's Iron" and revolutionized the whaling industry. A native of Richmond, Virginia, Temple never received formal schooling. In 1829, he married Mary Clark and established a family in New Bedford, Massachusetts, a major whaling center. As a metal worker at Coffin's Wharf, he studied the primitive design of the whaling harpoon, which whalers threw at the animal, then approached in small boats to complete the kill with lances.

In 1845, Temple replaced the less sophisticated harpoon model with a pivoting device set at right angles to the shaft. Held in place by a wooden pin, the mechanism set in the whale's jaw when tugs on the harpoon broke the pin and set the barb. This innovation secured the animal on the whaler's line. Because of his ingenuity, harpoon makers copied the device, and whalers increased their catch during an upsurge in the industry. Temple made no claim on the mechanism, but from 1848 to 1868 he earned a steady income from its manufacture.

An active abolitionist and temperance worker, Temple took an interest in improving life in New Bedford. In 1854, he built a brick blacksmith shop near Steamboat Wharf, but he did not survive its completion after suffering a fall over a plank left in the street by city sewer workers. Because he received permanent injuries to his arms and internal organs, he successfully sued the city for $2,000. However, Temple died before he could collect his compensation, and his wife and son were left in poverty, selling his property and goods to cover his debts.