Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/98

 86 it may commit, an attempt has been made to insinuate its uncertainty and even its inutility. But what science is there which would not be annihilated the moment that we made its truth and its usefulness to depend on the exact degree of correspondence that might subsist between the opinions of those philosophers who make it the subject of their study? If there exist some difference in the opinions entertained by the Abbé Haüy and myself on certain points in crystallography, what conclusion ought to be deduced from this circumstance? simply that this science, which on the one hand is supported by physics, and on the other by mathematics, and will perhaps at some future day become equally exact with the latter, has not yet obtained that certainty. Let us allow it to proceed towards this point, without obstructing its course. Difference of opinion when maintained with candour and decorum is perhaps not without advantage to the security and promptitude of its progress.

The laumonite has never hitherto been discovered except in a crystallized state, either in separate crystals, which is the most common appearance, or in an aggregation of crystals, forming masses of more or less considerable size for the most part irregular, and deeply striated externally.

Till the present time the laumonite had been observed only in the lead mine of Huelgoet in lower Brittany, in which it was discovered about twenty-five years ago by M. Gillet de Laumont.