Free The Dawn of Innovation by Charles R. Morris

temperature changes, the storm batterings, the salt everywhere. In 1721, no less an authority than Isaac Newton declared that it would be all but impossible for a solution to the longitude problem to come from the “Watchmakers.”
    The “Astronomical” solution, which Newton preferred, was at least as difficult. Sailors long ago learned to fix latitudes because the apparent path of the sun was so readily observed and easily measured. The so-called fixed stars also had a regular apparent path around the earth, but it was far too slow to be useful. Then there was the moon, which does have a regular pattern but an extremely complicated one that varies with the seasons, local variations in the earth’s magnetic fields, and much else. In principle, however, it was possible to precisely chart the moon’s position with reference to the fixed stars. If you looked up the moon’s position in a moon chart, it would tell you the exact time that pattern occurred over Greenwich. If you also knew your local time, you could calculate, again in principle, your east-west position. 13

    In principle. But observational instruments were not nearly accurate enough to track anything but the grossest positional changes of the moon with reference to the fixed stars. Even if they had the requisite accuracy, it would be very difficult to take such readings from the deck of a rolling ship. There were also some nasty mathematical complications to correct both your position and the reading from Greenwich to that of an observer at the center of the earth.
    Newton, for once, was wrong, and the watchmakers won. A self-taught genius named John Harrison built four candidate clocks over thirty years. They were highly innovative but extremely complex, and there were serious questions about their reproducibility. Nevertheless, all of them met the requirements for the prize, although it took the intervention of the king to secure Harrison his award, in part because of opposition from the astronomers who dominated the awards committee. l
    In the event, roughly a quarter century after Harrison’s death in 1777, watchmakers in both France and England were turning out affordable and reliable pocket-sized marine chronometers that enabled longitudinal calculations satisfactory for most purposes. Only a few of Harrison’s innovations were retained. Most chronometer makers chose to stick with traditional forms and mechanisms but learned how to execute them at new orders of precision.
    The astronomers got there too, by dint of an informal fifty-year international collaboration to build the necessary tables of lunar motion, along with the development of the sextant, the first instrument with the precision required for useful positional readings on the stars. The great Swiss mathematician Leonard Euler contributed practical methods for correcting the data, but they still took an expert some four hours of calculation.
Their practicality, that is, was hardly better than that of Harrison’s strange instruments. But the lunar charts were maintained and promulgated, and the correction math simplified, so by the first decades of the nineteenth century the two approaches were coexisting comfortably, with practical navigators frequently checking one against the other.
    It is a remarkable episode. A century elapsed between the 1707 Scilly Isles tragedy and achievement of a stable solution, but it was pursued consistently and diligently over that entire span. Although there was an international flavor to the longitude project throughout, it was driven primarily by the British.
    Its lasting stamp on British technology was something of an obsession for absolute mechanical precision, or what British machinists came to call “the truth.”

The Quest for Truth
    Until well into the nineteenth century, machinists’ tools typically lacked graduated measurement markings. In fact it was hard to do. All draftsmen knew how to make accurate