Besides the reading of papers, the club took several excursions. On Saturday they went to the pine-barrens of New Jersey, about fifty participating. On Monday a party visited the ballast-grounds during the morning, and upon their return inspected the library and herbarium of Mr. I. C. Martindale, of Camden, N. J. In the evening of the same day the Botanical section of the Philadelphia Academy of Science entertained the club, the Torrey Botanical Club of New-York City, and other invited guests, at the rooms of the Academy. About three hundred were present, and a thoroughly enjoyable time experienced. On the afternoon of Tuesday the club and its friends, in all about eighty, made an excursion to the Bartram Gardens, one of the most interesting historical spots to botanists in this country; and the club then adjourned. In reviewing the attendance of botanists in Philadelphia, and the work of the Botanical Club, there is much reason for congratulation. About a hundred entered their names on the register of the club as botanists, or about eight per cent. of the total attendance, one-half of whom are widely known for their attainments in the science. There was no lack of interesting papers and free discussion. Besides the important measures already referred to, the club was instrumental in securing the appointment of a permanent committee of the Association to encourage researches on the health and diseases of plants. But, above all, the augmented facilities for intercourse and acquaintanceship, and the impulse imparted to individual workers, through the influence of the club, are a sufficient _raison d'étre,_ and a promise of usefulness of the future.--_Science_. PETROLEUM WELLS. The theory of artesian and of spouting petroleum wells is entirely different. While the latter owe their operation to an internal pressure, due to gases accumulated within a confined space, the former are due to the pressure of a liquid which is flowing--a pressure caused by a sheet of water of unequal height; and they spout with so much the more force in proportion as the difference of level between the orifice and starting point of the sheet of water is greater.