Of Yankee Granite

The Obelisk

Few modern architects, engineers, or contractors are privileged to work in such distinguished company as did architect Solomon Willard, engineers Loammi Baldwin and Gridley Bryant, and contractor James Sullivan Savage, who designed and built the obelisk which is called the Bunker Hill Monument. They were associated with Daniel Webster and young Edward Everett, both of whom later became Secretary of State; with Thomas Handasyd Perkins (still revered in Boston as the man who endowed the Perkins Institution for the Blind), merchant prince of Boston, with the famous artists, Washington Allston and Gilbert Stuart; and their monument followed the classic lines of the model submitted by Horatio Greenough, a Harvard student, who later became a noted American sculptor.

To the amazingly talented architects and engineers of Egypt, 50 centuries ago, the Bunker Hill Monument would have been a simple structure to design and construct. To these ancient builders, it would have appeared to be merely a somewhat stubby shaft, devoid of the beautiful, deeply carved hieroglyphic record which ornamented their own obelisks from base to pyramidion (apex), and it would be a simple thing to erect. In fact, some would say that the monument is really not an obelisk, for it is built of many stones of a few tons weight each, whereas a single stone composed a typical Egyptian obelisk. Such stones sometimes weighed as much as 500 tons. They were transported hundreds of miles and by some now unknown method were erected to the vertical position by manual labor.

Like the Egyptians, the modern engineer would also call the monument easy to design and build. Today’s light, thin-walled chimneys of comparable height, pose much harder problems of stability against wind, and their designers feel fortunate when a chimney can rest on as firm a foundation as the glacial drumlin soil of Breed’s Hill. Why, then, was the erection of the monument considered such an unusual feat at the time?

The answer is obvious: the monument was built in the days of hand labor supplemented by animal power, and hand labor to the independent Boston mechanic of over a century ago did not mean hundreds of slaves tugging in unison to the drumbeat of an Egyptian timer, while an overseer cracked his whip. And the builders had determined to construct their monument of one of the hardest of building stones—New England granite—in the use of which there was then little precedent.

When the Bunker Hill Monument Association offered a prize of $100 for the best design of a monument, many plans, mostly of columns, were submitted. The Board of Artists of the Association (Daniel Webster, Gilbert Stuart, Washington Allston, Loammi Baldwin, and George Ticknor), who had to pass upon the submitted designs, favored the Greenough model based on an Egyptian obelisk of ancient Thebes. Although the directors had strongly favored a column, they yielded to the judgment of the Board of Artists and adopted the obelisk design instead.

Upon the adoption of the successful design, a committee, of which Loammi Baldwin was chairman, was appointed to “report a design of an obelisk.” Baldwin was a Harvard graduate, who had studied abroad under the patronage of Count Rumford.2 He had become one of America’s most prominent engineers. Baldwin was responsible for the construction of the dry docks at the Charlestown and Norfolk Navy Yards; planned a canal tunnel (later built as a railroad tunnel) through the Hoosac Mountain; and was active in surveys for an adequate water supply for Boston, in the day when Boston people got their water from wells. Baldwin and his associates on the committee first went to the Boston and Roxbury Milldam (now Beacon Street), from which the monument would be prominently visible across the Charles River. Miniature models of different dimensions were mounted on the Milldam fence and were viewed from a definite distance to the rear. In this highly practical manner, the size of the most striking monument on distant Bunker Hill was determined.

The Baldwin Report on the design of the Bunker Hill Monument, described as neatly handwritten, was one of the valuable documents in the literature of early American engineering history. It ranks with the “Private Canal Journal” of DeWitt Clinton,3 who promoted the Erie Canal; the report on American railroad standards of 100 years ago by Captain (later General) George B. McClellan of Civil War fame; Roebling’s report on the proposed Brooklyn Bridge; and similar historical documents that describe the methods from which the present processes of promotion and construction have sprung.

As shown in the table of dimensions which follows, the monument, almost exactly, is built to the dimensions of the Baldwin Report,4 which was influenced by the Greenough model.

Height, above ground	220 ft.
Sides of monument, at ground level	30 ft.
Sides of monument, at base of apex	15 ft.
Height of apex	12 ft.
Minimum wall thickness, at base	6 ft.
Diameter of circular interior, at base	18 ft.
Height of masonry elements:
78 main courses, each with height of	2 ft., 8 in.
5 courses in apex, each with height of	1 ft., 8 in.
Height of capstone	3 ft., 6 in.

Data from old records do not always check modern measurements. For example, a modern reference gives the height of the monument as 221 feet.

As described in the Baldwin Report, the circular winding staircase is composed of granite steps, starting with a width of about four feet and narrowing as the ascent is made. Baldwin called for “places of repose” (landings) at intervals. Modern architects call the part around which a circular staircase winds, the “newel.” Baldwin’s newel is a hallow wall, 10 feet in diameter at the base, about two feet thick.

Thus, the monument was designed by an engineer, not an architect. Baldwin violated a common rule for the proportions of ancient Egyptian obelisks, that the pyramidion should be as high as the base is wide, which is one reason why the Washington Monument is so beautiful. One regrets that architect Willard, who picked up where Baldwin left off, did not see fit to modify the Baldwin lines. There seems never to have been any question as to the monument’s material: granite, the native New England stone. Although we admire the Bunker Hill Monument for its somber strength, it cannot be called a structure of beauty, as is the lighter-tinted and finer-textured marble Washington Monument, with its sharper apex.

We can also speculate on why Baldwin made the monument wholly of granite. At today’s prices, the circular inner surface of the shaft and the circular chimney, or newel, around which the stone staircase winds, would be of tremendous cost. The dressing of the stone for a square inner area would be much cheaper.

Before criticizing Baldwin on his ponderous stair design, which could be replaced by a light, modern fire escape, we should look at the status of the tiny American iron industry of his day. The ironmasters were recovering from the decline of activity in the War of 1812, during which they had lost their British market. Baldwin would know that certain early railroad promoters estimated that granite tracks mounted with iron plates would be less expensive than the English-rolled rails, which the Americans could not produce. With masons in Massachusetts receiving about $0.18 an hour, granite was considered cheaper than iron. Baldwin therefore designed his stairway of granite, with a massive granite chimney “newel” to support the inner ends of the treads. Long before the monument was completed, however, a square staircase of either cast iron or wrought iron could have been produced, economically, by American ironmasters. It was then too late to make the change, however.

At about the time of the completion of the monument the first mechanical elevator was exhibited, but there was no room for an elevator at Bunker Hill—the newel was in the way. To climb a few score steps would be an easy task to our sturdy forebears, and to say that one has “climbed the Bunker Hill Monument” is a boast that hundreds of thousands of tourists to Boston have been proud to make for over 100 years. Baldwin may have been right again, as he usually was.

Baldwin specified that the monument should be square with the compass, a common Egyptian practice. As built, however, it is oriented to fit the redoubt (southeast corner) of the battle fortification. Structurally, Baldwin designed a sound foundation, 12 feet deep, built of six courses of stone with no small rubble that might deteriorate through the years. He specified that the starting level of the base of the monument should be established at the best elevation to avoid an uneconomical distribution of the excavated earth; today we would say that he balanced cut and fill.

The modern building contractor finds the estimate that went with the report both practical and quaint. He will find that the digging of the pit for the foundation of the monument was figured in “squares,” at $2.00 each; and since a square meant eight cubic yards, hand excavation was therefore priced at $0.25 per cubic yard. This price must have included the expense of shoring; also the pumping that such a deep pit would require. Baldwin proposed to dig a deep well on the site (today called a test pit), which would not only indicate the adequacy of the soil, but would also furnish water for construction purposes. Much water would be needed to mix the lime and sand mortar for the monument as well as for the Roman cement, for which the estimated 100 casks were figured at $7.00 each.5

Masonry was then estimated in “perches,” and by a little arithmetic, the modern contractor will learn that a perch was then equal to 25 cubic feet, or nearly a cubic yard. The 784 perches of masonry for the foundation were priced at $10 per perch, including “stones, hammering, mortar, laying, etc.”

The report of Baldwin contains no computations on the structural stability of the monument. If the modern structural designer wishes to investigate how near the safe limit the monument has been tested by Boston’s occasional hurricane winds, he has available the major dimensions given in the Baldwin Report, and the drawings of Willard’s classic Plans and Sections of the Obelisk from which to make this simple computation.

Such computation shows that the monument is so heavy that a hurricane wind has an almost imperceptible effect on its stability. When it is subjected to a 100-mile-per-hour wind, the resultant force is displaced only a fraction of a foot from the center of the 50-foot-wide foundation. The maximum load on the soil is about five tons per square foot—a safe bearing load on “the bed of clay and gravel which composes the soil of the Hill” as described in an old account. The same account speaks of “great pains having been used in loosening the earth, and in puddling and ramming the stones.” Surely, our construction ancestors would not have purposely disturbed the underlying soil, in an attempt to improve upon the natural bearing strength of one of the firmest of foundations: glacial hardpan. Like any good builder, they were undoubtedly merely puddling with water the earth backfill around the completed foundation.

Baldwin knew that granite would not deteriorate when exposed to the alternately hot and cold temperatures of Boston. Half a century later, the engineers who transported an Egyptian obelisk (one of the Cleopatra’s Needles) to Central Park, New York, learned that the lovely textured syenitic granite of the Nile Valley was markedly inferior to New England granite in weather resistance, although it had kept its surface intact for centuries in the mild climate of Egypt. To protect Cleopatra’s Needle in New York, a paraffin coating was found necessary.

Baldwin soon resigned from the building committee, partly because of the press of other work, but largely in protest against a clause which made its members, all of whom freely donated their services, financially responsible for the estimate. Promptly after accepting his resignation, the directors revised this clause. In reviewing the quaint old methods, the question arises: Would modern estimates be more accurate if the consulting architects and engineers had to pay for overruns?

Notes

2 The famous scientist, Benjamin Thompson, of Woburn, Mass., who later became an English citizen, and who established the fact that heat is a form of motion.

3 William W. Campbell, Life and Writings of DeWitt Clinton (New York: Baker and Scribner, 1849).

4 Measurements given above have been taken from: Baldwin Report (1825)—Loammi Baldwin; Plans and Sections of the Obelisk on Bunker’s Hill (1843)—Solomon Willard; History of the Battle of Bunker’s (Breed’s) Hill (1875)—George E. Ellis.

5 “The use of natural cement was introduced by Mr. Parker, who first discovered the properties of the cement-stone in the Isle of Sheppy, and took out a patent for the sale of it in 1796, under the name of ‘Roman Cement.’”—Edward Dobson, Rudiments of the Art of Building (London: John Weale, 1854).