Gale was a graduate of Union College in Schenectady, New York. After graduating, he devoted himself to the pursuit of chemistry and became a professor in several institutions of learning. In 1833 he made a geological survey of Manhattan Island, and not long afterward was appointed professor of chemistry and mineralogy in the New York City University.

In 1836, he formed the acquaintance of Samuel Morse, and by his familiarity with the discoveries of Professor Henry was enabled to render his colleague's project of an electromagnetic telegraph successful in operation. In 1846 he came to Washington, and for eleven years was an examiner in the United States Patent and Trademark Office in charge of the department of chemical inventions. In 1857, having been removed from that office, he practiced in Washington, D.C. for some years as an expert and attorney in chemical applications. He is buried in the Washington Congressional Cemetery.

• Telegraph in United States history

• Works by or about Leonard Gale at Internet Archive