Some of the most valuable inventions have descended to us without the names of their authors having been preserved. We are the inheritors of an immense legacy of the results of labour and ingenuity, but we know not the names of our benefactors. Who invented the watch as a measurer of time? Who invented the fast and loose pulley? Who invented the eccentric? Who, asks a mechanical inquirer,[13] "invented the method of cutting screws with stocks and dies? Whoever he might be, he was certainly a great benefactor of his species. Yet (adds the writer) his name is not known, though the invention has been so recent." This is not, however, the case with most modern inventions, the greater number of which are more or less disputed. Who was entitled to the merit of inventing printing has never yet been determined. Weber and Senefelder both laid claim to the invention of lithography, though it was merely an old German art revived. Even the invention of the penny-postage system by Sir Rowland Hill is disputed; Dr. Gray of the British Museum claiming to be its inventor, and a French writer alleging it to be an old French invention.[14] The invention of the steamboat has been claimed on behalf of Blasco de Garay, a Spaniard, Papin, a Frenchman, Jonathan Hulls, an Englishman, and Patrick Miller of Dalswinton, a Scotchman. The invention of the spinning machine has been variously attributed to Paul, Wyatt, Hargreaves, Higley, and Arkwright. The invention of the balance-spring was claimed by Huyghens, a Dutchman, Hautefeuille, a Frenchman, and Hooke, an Englishman. There is scarcely a point of detail in the locomotive but is the subject of dispute. Thus the invention of the blast-pipe is claimed for Trevithick, George Stephenson, Goldsworthy Gurney, and Timothy Hackworth; that of the tubular boiler by Seguin, Stevens, Booth, and W. H. James; that of the link-motion by John Gray, Hugh Williams, and Robert Stephenson. Indeed many inventions appear to be coincident. A number of minds are working at the same time in the same track, with the object of supplying some want generally felt; and, guided by the same experience, they not unfrequently arrive at like results. It has sometimes happened that the inventors have been separated by great distances, so that piracy on the part of either was impossible. Thus Hadley and Godfrey almost simultaneously invented the quadrant, the one in London, the other in Philadelphia; and the process of electrotyping was invented at the same time by Mr. Spencer, a working chemist at Liverpool, and by Professor Jacobi at St. Petersburg. The safety-lamp was a coincident invention, made about the same time by Sir Humphry Davy and George Stephenson; and perhaps a still more remarkable instance of a coincident discovery was that of the planet Neptune by Leverrier at Paris, and by Adams at Cambridge.