7 The 100 Most Influential Inventors of All Time 7

on copper plates was not proving very successful when an

accident led to his discovery of the possibilities of stone

(1796). Senefelder records that one day he jotted down a

laundry list with grease pencil on a piece of Bavarian

limestone. It occurred to him that if he etched away the

rest of the surface, the markings would be left in relief.

Two years of experimentation eventually led to the dis-

covery of flat-surface printing (modern lithography, from

Greek lithos, “stone”). Senefelder closely held the secret of

lithographic printing until 1818, when he documented his

discovery in Vollständiges Lehrbuch der Steindruckerey (1818;

A Complete Course of Lithography).

Senefelder later accepted an offer from a music pub-

lisher, Johann Anton André, to set himself up at Offenbach

and train others in his lithographic process. In later years

the king of Bavaria settled a handsome pension on

Senefelder.

Sir William Congreve

(b. May 20, 1772, London, Eng.—d. May 16, 1828, Toulouse, France)

S

ir William Congreve was an English artillery officer

and inventor, best known for his military rocket, which

was a significant advance on earlier black-powder rockets.

It provided the impetus for an early wave of enthusiastic

utilization of rockets for military purposes in Europe.

Congreve based his rockets on those used by the Indian

prince Hyder Ali against the British in 1792 and 1799 at

Seringapatam. In 1805 he built a rocket 40.5 inches (103

cm) long, with a stabilizing stick 16 feet (4.9 m) long and a

range of 2,000 yards (1.8 km). Congreve’s rockets were

used to bombard Boulogne, Copenhagen, and Danzig in

the Napoleonic Wars and in the British attack on Fort

McHenry, near Baltimore, in 1814, which inspired Francis