Up-To-Date Quarry (Circa 1825–1843)
From various old American and English records of masonry construction, it is possible to construct an account of how the stones for the Bunker Hill Monument must have been quarried and dressed. The old names are used for the tools and methods, and the modern mason will find many of these old descriptions quite familiar.
The hornblende granite of the Quincy region was (and is) of very uniform texture and varies only in color, from gray to dark gray. In Quincy, Willard would find that both “sheet” and “boulder” quarry formations occurred: the joints in the ledge of the sheet areas making the granite appear as if stratified, and hence more easily removed; but the huge, rounded boulders in the other areas, measuring up to 40 feet across, had no joints. Rows of holes were drilled by hand (at least 25 years would elapse before practical power-rock drills became available) and large blocks loosened from the ledge or boulder, probably by wedges, possibly by light blasts of gunpowder. At this stage the quarried block was called “quarry-pitched.” Stone of the smaller size for the monument was split from these blocks along lines of holes in which wedges were driven. These were probably of the plug-and-feather type, in which an iron wedge with an acute angle is fitted between two semicircular iron feathers, which taper in the opposite direction to that of the wedge, and thus fit the hole drilled in the stone, nicely. Granite has no cleavage planes, like slate; but a routine of smart taps on the plugs, back and forth along the line, soon splits the stone along a fairly smooth face. Two lewises (an ancient device), attached at about the quarter points of the top of the stone, were used to lift it. Three members make the lewis: a flat center bar with an eye at the top, the center bar being flanked by two wedge-shaped side pieces which are thicker at the bottom of the hole, and these also have eyes at the top. The wedges are inserted first, then the center bar slipped between; thereafter any lifting pull on the three bars is bound to expand the lewis to fill the hole and lift the stone, for the hole is drilled wider at the bottom than at the top.
With Solomon Willard’s well-rendered isometric drawing of each stone for a guide, the stonecutter dressed it, first selecting the best face for the “bed” (bottom) and hammered it to a plane surface, determined by shallow channels (chisel drafts) cut diagonally across the stone.
From this surface, the stonecutter laid out the other faces, including the “build” (top), by his good mason’s square or template. The texture of the visible face was “tooled,” that is, the marks of the chisel remained visible. Quincy granite is a quality product, taking a high polish, but the builders of the Bunker Hill Monument desired no polish on their monument. Today, the surface of the monument shows faint, well-weathered lines, like those produced by the modern bushhammer, which has a head made of several thin steel plates bolted together, each sharpened to a cutting edge. In England during the period, flat iron bars with rough edges were in use to saw softer stone than granite, and at Quincy, Willard experimented with dressing machines. The conclusion may be drawn, however, that the stones which we now see on the monument were undoubtedly shaped to their present dimensions by hand.
Today, 110 years after its capstone was put in place, the Bunker Hill Monument stands as an impressive testimonial to the conservative judgment of its designer, Loammi Baldwin, and the painstaking fidelity of the man who supervised its construction, Solomon Willard. An engineer familiar with its maintenance states that there is no evidence of settlement, and that a check by surveyor’s transit revealed no signs of misalignment. Its joints occasionally need pointing, the last pointing being performed about 20 years ago. Various iron or steel members of the observation chamber have had to be replaced. Its lightning rod has been in place for many years, but there is no readily available record to check whether the monument has ever been struck by lightning. With their empirical methods of design and their crude, mostly hand-operated, construction apparatus, our forebears built a sturdy structure, which, barring an earthquake, should last for centuries.