On a sunny Friday morning in August 1853, at Valley Falls station near Pawtucket, R.I., Frederick Putnam, the conductor on the southbound train to Providence, R.I., looked at his watch and saw he was late.
Ahead he could see the Boston switch, where northbound and southbound trains had to take turns using the same single-track line.
Putnam knew that in a few minutes a train would be coming north on the same track he had to use. He looked at his watch again. It showed that if he moved fast, he could get the train through.
Putnam gave the engineer the signal to start. The train built up speed, rounded a curve and came face to face with the northbound train running full throttle.
``The first car of the (Providence-bound) train was smashed to pieces, the tender having been driven through it,'' The Hartford Courant reported the next day. Fourteen people were killed and 60 injured, ``their limbs broken and their bodies battered.''
The synchronization of trains was becoming a precious, life-preserving commodity in the industrial 1850s. The year 1853 had brought 65 train wrecks and 176 deaths - more than twice the totals for the previous 20 years. By the time of the Pawtucket disaster, the public was getting sick of such carnage.
``This matter of time was absolutely crucial to the railroads,'' says William Andrewes, curator of Harvard University's Collection of Historical Scientific Instruments. ``Quite simply, the railroads had to, literally, buy time in order to prevent accidents.''
There was no standard time for the world, the United States or the region, and there were hundreds of variations in local time.
When it was noon in Washington, D.C., it was 12:23 and 58 seconds in Boston, 12:17 and 29 seconds in Hartford, Conn., and 12:16 and 30 seconds in New Haven. Railroads ran on the time of the city where the line's head offices were located, creating a tangle of schedules.
The conductors' watches, synchronized with watches in the station masters' offices, could, like Putnam's, register fatal inaccuracies.
``The Most Reliable Time,'' an exhibit at the instrument collection in Harvard's Science Center, displays an innovative link between 19th-century clockwork technology and astronomy - and between science and commerce - devised to try to synchronize time.
While the railroads were willing to pay to know the accurate time, William Cranch Bond, a Boston clockmaker and founder of the Harvard College Observatory, was willing to give it away.
Firm believers in the unity of commerce and science, Bond and his son, George, set up the first system of regional standard time in the world. And they did it more than a year before Greenwich, England, set up its own standard time system.
``Bond treated time as a public thing,'' says Carlene Stephens, who is writing a book on the Bonds and is a curator in the Division of Engineering and Industry at the Smithsonian's National Museum of American History.
Bond and other clockmakers would get the time by marking the precise moment that certain ``clock stars'' crossed the meridian - the imaginary line passing through the highest point of the heavens, marked by a cross hair in a telescope.
So clockmakers had to be astronomers, too, and for their observations and the quality of their clockwork devices, the Bonds won a tremendous reputation for accuracy.
The synchronization of time already had gone public to some extent. In some places, cannons were fired precisely at noon. In others, ``time balls'' were dropped. The balls fell from the towers of public buildings at a prearranged time so that every ship in port could adjust its chronometer accordingly.
But the railroads, which traveled at then-breathtaking speeds of 40 mph or more, needed more accurate readings, and needed them more frequently.
The answer lay in figuring out a way that accurate time could be delivered to a great many people all at once.
In 1844, Samuel F.B. Morse invented the telegraph, discovering that, by opening and closing electric circuits, he could send messages over wires.
Suddenly there was a way to get information instantly from one place to another.
This is where the Bonds got into the act, combining a telescope, a clock and a new kind of recording device: the drum chronograph.
The device was a metal drum about the size of a restaurant-sized can of pears. It was the world's first self-recording instrument, invented in Europe to measure the velocity of artillery shells.
A piece of paper was wrapped around the drum, which was slowly rotated by a clockwork mechanism. The same mechanism drew a glass pen filled with ink slowly across the paper surface, making a gradual spiral.
Nearby was a regulator clock. Inside the clock, as in all mechanical clocks of the period, was an escapement wheel: a toothed brass wheel designed to catch and release a horseshoe-shaped hook called an escapement. This mechanism - which makes the clock tick and tock - was powered by the force of weights and a swinging pendulum.
A dry-cell battery passed an electric current through the escapement. Each time the escapement and the escapement wheel came into contact, the electrical circuit was completed. Electricity passed through a wire from the clock to the drum chronograph, where it activated an electromagnet, which gave the glass pen a little jerk.
As the drum turned slowly, the ticking of the clock jerked a series of tiny V's. The result was a precise record of the time kept by the clock.
But another wire led to the electromagnet. It came from a telegraph key on a table next to a transit - a telescope used to observe the transit of clock stars across the meridian.
So the ticks and tocks of the clock could go wherever a telegraph wire could reach.