Mr. Thomas Moy remarked that the popular mind was peculiarly obtuse to simple facts which should be easily grasped, and that even scientific men failed to appreciate the importance of the demonstrations whiqh had been worked out by that Society. The amount of success with models, he contended, were so palpable, that men of capital did not exhibit much wisdom in their non-encouragement of efforts on a larger scale. If a tin box of one cubic foot capacity, as shown in diagram No. 1, were filled with gas capable of raising one ounce to the cubic foot, and if the tin of which it was made weighed one ounce per square foot, then it would weigh six ounces if filled with air, and only five ounces if filled with gas.