itself into a compact ball when touched; the other Oniscus Asellus which does not roll itself into a ball when at rest. Large quantities may be caught wherever they abound, by placing two tiles or boards over each other, between which they will crawl as the dawn of morning approaches, to conceal themselves; and tiles laid over old cabbage leaves form excellent traps. Journeyman. I know that a toad if kept in a frame, will soon exterminate woodlice, ants, &c., but a pan of water should be put in with the animal. Mr. B. You will now understand from our conversations on Entomology that the practical result to be derived from a knowledge of the subject is to be able to distinguish your friends from your enemies in the insect creation, and that the practice of some of the old florists to char or roast their compost before using it, was an effectual way of destroying the eggs and grubs of insects. And also that the practice of destroying moths and other injurious insects, as soon as they are seen, tends to diminish the numbers considerably, as each female, and the females are more numerous than the males, would, on an average, be the parent of fifty others if allowed to deposit her eggs. Although snails and slugs do not belong to the category of insects, being classed among the vermes or worms, nevertheless, I will conclude our lesson this evening with a few particulars about them. The Slug Limax, is without a shell; there are sixteen British species, but the Limax ater alba, and Limax hyalinus are the most common in gardens. The Snail Helix is a numerous genus, and, like the slug, very destructive to plants and fruit; both snails and slugs are hermaphrodite, having both sexes united in one individual, they lay their eggs with great care in the earth, and the young ones are hatched, the slugs without shells, and the snails with shells, completely formed. The most common species is the Helix hortensis, or garden snail. Many caustic substances, as you are aware, such as lime, soot, &c., have been used to destroy them, but the most effectual way of getting rid of them is by hand-picking, when collected under decaying leaves, or haulm laid down on purpose to attract them. Land Surveping. PROBLEM VII. To divide a piece of land of uniform value among any number of claimants, in proportion to their respective claims. Rule. As the sum of the proportional parts is to the whole quantity of land to be divided, so is each proportional part to its respective share. Example 1. It is required to divide 566 acres of land among A, B, and C, whose shares are respectively proportional to the numbers 5, 7, and 9. 21) 2830 (134 A's share 21) 3962 (188 B's share 21) 5094 (242 C's share. 21 21 42 5+7+9=21 the sum of the proportional parts: as 21 596 :: 5: 21: 566 :: 7: =188 2 2014 B's share. 21 =242 2 11 C's share. 566 0 0 Proof. Example 2. There is a common pasture belonging to three persons, A, B, and C, containing 37.0565 acres, capable of feeding eighteen cattle, of which A has a right to put in four, B six, and C eight. Now, supposing the parties agree to have the pasture divided into three parts, proportional to their right of pasturage, what number of acres will fall to each person's share. Here, as the whole number of cattle is to the whole number of acres, so is the number of cattle belonging to each person to the number of acres which falls to his share. To divide a common &c., which is not of uniform value, among any number of proprietors, in the proportion of their respective claims. Rule. Divide the numbers which express the proportion of the parts by the sum denominating the relative value of the land which each claimant is to take; then, as the sum of the quotients thus obtained, is to the whole common or quantity of land to be divided, so is each respective quotient to the share thereto belonging. Example. It is required to divide a common consisting of 780 acres among A, B, and C according to the values of their respective estates, which are estimated at 1000, 3000, and £4000 respectively, the ground in their respective shares being valued at 5, 8, and 10 shillings per acre. To measure a rectangular pit, the angles whereof are right ones, or nearly so, and the sides and backs nearly straight. Rule. Multiply the mean length of the pit's body by the mean breadth, and that product by the mean depth. This last product will be the content in cubical yards. Example. To find the content of a pit, the sides whereof are nearly perpendicular, and the angles nearly right, that is, neither much obtuse, nor acute. The different lengths to be taken by a string or a measuring tape in the pit, about the middle of the depth, the different breadths to be taken in like manner, and the depths to be taken at every one or two yards from each side of the pit, according to the size of the pit. The following depths were taken at every two yards from each side of the pit. Answer-562.248 Cubical yards in the body of the pit. Geology. Mr. B. We finished our last conversation with an account of the important uses of coal and iron in administering to the supply of our daily wants. One remarkable characteristic of the vegetation of the coal period is the uniformity or monotory of its plants. In our age we find that different countries, in different climates, produce different plants; but in the carboniferous era, the same plants grew in Germany, Belgium, France, England, North-America and Australia. This fact proves a remarkable uniformity of climate at that period. When North-America was discovered there were found in it only two wild plants that agreed with the vegetation of Europe. But of 53 kinds of plants found in the North-American coal beds 35 are common in the European coal fields. In the woods of that period grew a remarkable pine tree called Pinus Succinifera which produced the fossil resin called amber. This amber is of great interest to the Geologist as it often encloses specimens of insects, spiders, flies, small crustaceans, leaves of trees, &c., which are monuments of the flora and fauna of that period. Upwards of 800 species of insects |