| The schistous | 2·81. |
| The marble | 2·86. |
| The gypsum | 2.32. |
In the absence of a precise knowledge of the quantity and position or each of these three component parts, we may take the mean, 2.66, of their several densities as approximatively the density of the mountain, = δ. We have then
Δ = 5.02 δ × 39.115414394 × ·0076 = 4.77,
a result differing little from that of Cavendish as recently corrected by Dr. Hutton, and still less from that of the Schehallien experiments.
The most hypothetical element of this calculation is the width assigned to the base of the mountain; but by the very nature of the question, it has but little influence on the final result; since, by even doubling the assigned diameter, the total attraction would not be altered a twentieth. In regard to the mean density of the mountain, if it were taken at 2.75, instead of 2.66, that of the earth would result 4.94, instead of 4.77, as given above.
E. S.
Transactions of the Horticultural Society. Vol. vii. Part 1. 4to. London, 1827. pp. 208. [◊]
I. Observations upon the Growth of Early and Late Grapes under Glass. By Mr. James Acon. [◊]
FEW gardens are to be found in which bunches of fresh ripe grapes can be gathered every day in the year: notwithstanding the importance of the fruit to the luxurious, and the facility with which the vine submits to the artificial climate of the forcing-house. Nothing is easier than to secure crops of grapes in a vinery during the spring and summer months; but it is far more difficult to obtain them in the last and earliest seasons of the year, when the plants would [p160] naturally be in state of torpidity. It is well known that this desirable purpose is attained in great perfection in the garden of the Earl of Surrey, at Worksop Manor; and the management there practised is the subject of this paper.