June 1973 | Volume 24, Issue 4
Every schoolchild knows that the Liberty Bell is cracked; the crack is almost as famous as the bell itself. But just when and why the crack appeared is a much more esoteric matter. It is sometimes assumed, patriotically but mistakenly, that the bell cracked out of overenthusiasm while being rung to celebrate the Declaration of Independence in 1776. Somewhat more solid evidence suggests that it broke in 1835, either in July while tolling a knell for Chief Justice John Marshall or on Washington’s Birthday, when a group of small boys pulled too energetically on the rope. One of the boys, Emmanuel Rauch, was interviewed in 1911 and stuck to that story, observing besides that for any funeral the bell’s clapper would have been muffled and unlikely to cause damage. In 1846 an attempt was made to put the great bell in ringing order by drilling out the edges of the crack to prevent their rubbing together. This worked about as well as the dentistry characteristic of the period; and when the bell was rung on February 23 of that year (Washington’s Birthday having fallen on Sunday), the crack suddenly split open farther. Since then the only sound heard from the Liberty Bell has been a disappointing thunk created by tapping it gently with a small mallet on triumphant occasions like the Allied invasion of Normandy in 1944.
But why did the bell crack in the first place?This highly technical question has recently been given extensive study by a professional metallurgist, Dr. Alan R. Rosenfield, an .expert on metal fracture who is associated with the Battelle Memorial Institute in Columbus, Ohio. He has come up with some interesting facts and explanations. In general, he points out, “bells are necessarily made out of brittle metal, and they often break. Even Big Ben is slightly cracked. ”
The Liberty Bell is a moderately large one, with a lip circumference of twelve feet and a total weight of over a ton. In 1751, when the Assembly of the Province of Pennsylvania wanted a suitable bell for the newly completed belfry of their State House in Philadelphia, they ordered one from the Whitechapel Bell Foundry in London—presumably because they did not trust any foundry in America to design such a large bell. It arrived at Philadelphia in the late summer of 1752. To everyone’s surprise and dismay it promptly cracked “by a stroke of the clapper without any other violence, as it was hung up to try the sound. ”
To save a round trip to England two local foundrymen—John Pass and John Stow—were engaged to recast the bell. While they do not appear to have been experienced bell founders, they knew that the ideal bronze alloy for a large bell should contain about 77 per cent copper and 23 per cent tin. They also knew that an increase in the proportion of tin improves the tone and resonance of a bell —one might say its tintinnabulation—but makes it more brittle. They therefore reasoned that their bell, as received from England, probably contained too much tin. With that in mind they made a mold from the original bell to preserve the design, melted down the metal, added one and a half ounces of copper per pound of bronze, and recast. The bell that resulted, however, was judged to have poor tone, and they allegedly tried again—this time adding about one-fourth per cent silver in order to sweeten the tone. (“This,” comments Dr. Rosenfield, “reminds one of the story that the Great Bell of Peking owes its sweet tone to the sacrifice of a maiden who jumped into the molten bronze. Silver does little or nothing to improve the resonance of bell metal, nor do maidens.”) When Pass and Stow’s second attempt came out of the mold, it was deemed acceptable if not altogether satisfactory, and it was hung in the State House belfry —its destiny as America’s Liberty Bell, of course, undreamed of.
Pass and Stow, perhaps sensing that this was their one chance for renown, added their signature to the bell in raised letters no less prominent than those used for the inscription around the crown: PASS AND STOW / PHILAD A / MDCCLIII . The crown inscription, chosen when the bell was originally ordered from England, reads: PROCLAIM LIBERTY THROUGHOUT ALL THE LAND UNTO ALL THE INHABITANTS THEREOF LEV [iticus). XXV V S X ./ BY ORDER OF THE ASSEMBLY OF THE PROVINCE OF PENSYLVANIA FOR THE STATE HOUSE IN PHILAD A . This, including the misspelling of Pennsylvania, presumably was reproduced by the mold just as it had appeared on the original bell. Without the inscription, clearly, the bell would never have been adopted by the American people as a prime symbol of the Revolution. As a matter of fact, this was slow in coming: the bell was not commonly known as the Liberty Bell until the l840’s and in 1828 it was even offered for sale by the City of Philadelphia as salvage. (It was refused because it was thought too expensive to move.)
But back to the crack. Dr. Rosenfield points out that, quite aside from orthography, there were both visible and invisible defects in the bell. Pass and Stow were not skillful enough to produce a bell with a uniformly smooth surface: there are numerous pockmarks and some seams. Moreover, modern metallurgical analysis of a small sample has indicated two defects in the metal itself: it still has too much tin (24 per cent by weight), and it contains many nonmetallic impurities, globs of lead, and small voids. Any one of these irregularities, or a combination of them, could have started the fatal crack under the impact of the bell’s clapper.
On top of this, the Liberty Bell had a rough time during the Revolution: when the British approached Philadelphia in 1777, it was loaded on a wagon and jolted over bad roads to Allentown for safekeeping until 1778. It is said to have been dropped at least once en route, which may have produced an incipient, microscopic crack. Finally, any big bell is subject to metal fatigue—the gradual deterioration of part of the bell under a repeated number of sinkings; and the Liberty Bell’s structural defects may have led to a fatigue crack some time in its first fifty or sixty years of existence. This would not have impaired the tone of the bell until the crack reached a critical size and then fractured rapidly and catastrophically, as apparently it did in 1835. Alternatively, a single overload—an extra-heavy blow from the clapper—could have fractured the bell all at once.
Could the Liberty Bell be melted down and recast so that it could ring again? Certainly, our expert says; and in fact the Whitechapel Bell Foundry, still in business in London, offered to do just that in 1945. The offer was politely turned down by the federal government. The crack, it would seem, has become as sacred as the bell itself, and to remove it would be like subjecting the honorable battle scars of an old soldier to plastic surgery.