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Letters to the Editor

since there could be good reasons for the firmament to revolve around the earth rather than for the earth to rotate on its axis. All of these astronomical comments seem to have been removed from most copies of the book and the dedicatory epistle simply shortened by that amount. Although no one, as far as I know, has noted this variation before, it is a change that can be fairly easily examined. The recent republication of Questions harmoniques (1972) contains the shortened form of the dedication. The longer version, however, is to be found in Mersenne's Correspondance.25 While other variations are mentioned in Lenoble&s bibliography of Mersenne's works, the ones discussed here are perhaps the most significant and the most likely to lead to confusion. As the republication of Mersenne's books continues, however, more variants will no doubt be discovered, requiring more textual comparisons in order to elucidate further Mersenne's ideas and the intellectual crosscurrents of the period. It is hoped that the present note is a first step in pointing out alterations in Mersenne's works and the reasons for them.