On paper, Willard had performed the painstaking task of dimensioning every stone, each with its top (the build) a little narrower than its bottom (the bed), so that the true taper of the obelisk would be maintained. To set the stone to line was the chore of the erecting force. On the top of the stone already in place lime mortar was spread, enriched with hydraulic cement, and with a sprinkling of iron filings. (A popular, modern, commercial waterproofing compound utilizes the fact that, upon oxidizing, iron particles mixed with the cement mortar expand, thus reducing the voids and producing a denser mass when the mortar sets.)
Temporary wooden wedges would be placed at the corners of the stone already in place, to support the heavy new stone until the mortar had hardened. When the ponderous stone had been speedily raised from the ground to a level a few inches above the mortar, the engine would be stopped; the derrick adjusted to right or left, and in or out, until the stone was very closely in line. Next, riggers would push on the bridle chain which attached to the two lewises in the stone’s top surface, guiding it to its true position in its gentle descent as the engine lowered it the few inches needed to bed it. A tiny fraction of an inch “out-of-line” would be serious, for such errors if repeated, or if not compensating, would visibly throw the monument out of line. On a light stage high above the ground, bracing themselves against gusts of wind, the riggers would be intent on the necessity for such accuracy, but not forgetting their own safety, for no careless workman could work for Savage. They would remember that, while laying the last stone of the 12th course, at the southwest corner, one man had been pushed off (the only death on the project).
Profitable Project
Happily, the good riggers raised their monument, course by course, to the top. They were under a boss who knew his trade, and he was making money—the sign of content on any construction project. (Savage made some more money after the monument was finished, when he retained the steam engine that had been used for hoisting stone, for the purpose of raising a passenger car to the top. For the car ride he collected $0.20, as against the $0.125 for visitors who climbed the stairs.)
The practical riggers would not be disturbed at the proposal, advanced when the monument neared its top, that the apex be modified to form a platform to accommodate visitors. Aesthetic Bostonians were much disturbed at this proposal. Happily, the Bunker Hill Monument Association voted down this architectural atrocity.
High Capstone
On Saturday, 23 July 1842, several hundred of our early rising Bostonian ancestors rose earlier than usual to arrive at the monument at 6:00 A.M. On the ground at the base, they studied the capstone; a small stone pyramid, three feet, six inches high, stoutly lashed to the derrick hook, and with an American flag at the top. Standing on the capstone, firmly grasping the hoisting rope, Colonel Charles R. Carnes waited for the signal to hoist. When the clock struck six, a signal gun was fired, and the capstone, bearing the good colonel, started up. In 16 minutes it had reached the top; at 6:30 A.M. it had been bedded, and a national salute announced to all Boston that the Bunker Hill Monument was completed.
By railroad, great multitudes came to Boston for the dedication of the Bunker Hill Monument, nearly a year later, on 17 June 1843. Unlike the time of 18 years earlier, when the cornerstone had been laid, stagecoaches were not the main conveyance for visitors to Boston. Indeed they were decidedly on the way out, and would soon be but symbols of an era of traveling discomfort, as the railroad completely took over. President Tyler and his cabinet attended; Daniel Webster matched with sonorous eloquence his famous speech at the laying of the cornerstone, and there were still 13 very aged surviving veterans of the battle able to attend.
Foucault’s Experiment
Seven years later (1850), two Harvard professors checked with elaborate apparatus, paid for by members of the Bunker Hill Monument Association and the Massachusetts Charitable Association, the famous experiment of Foucault which used a long pendulum to prove the daily rotation of the earth. Suspended in the newel by an annealed wire, 210 feet long, the oscillations of a pointer, attached to a 31-pound British cannon ball relic of the battle, were observed; and its plane of swing was seen to revolve during the day from right to left of the observer. A sudden shower on a previously bright day complicated the experiment, until Professor Eben N. Horsford discovered the reason. Cooled by the rain the monument’s exposed face contracted; its apex moved correspondingly and carried the point of suspension of the pendulum with it. As observed years later on the Washington Monument, Horsford deduced that the side of an obelisk, exposed to the hot sun, expanded, and that its apex followed the sun in the sun’s travel from east to west. Such motion is tiny, and the ingenuity of the apparatus to observe it was notable. The path of the orbit of the bob, registering both the earth’s rotation and the effect of varying heat on the monument’s sides, was described as an irregular ellipse with major axis of one-half an inch.