Son. It is also said that no one should attempt to draw any conclusion from what he thinks he sees in a microscope until he has familiarized himself with its use by some weeks' diligent practice. You may see anything in a microscope or nothing according to the amount of skill and intelligence you bring to the aid of your observation. The larvæ of the genus Byrrhus are found upon plants or in the bodies of half-decayed animals. They often undergo their transformation in insects that have been preserved, and reduce them to powder. The perfect insect has some resemblance to the lady-bird tribe. The insects of the next genus, Silpha, are mostly found amongst substances in a state of decay, frequenting dunghills, carrion, &c., and depositing their eggs chiefly in the latter, which, for greater security, they contrive to bury under ground. Several of these insects have been seen working together till they have accomplished the task of dragging under the surface the body of a mole in the space of an hour, so that no trace of it was to be perceived. Foreman. I have seen one of them bury a dead thrush in a garden in Kent. Mr. B. The larvae of the genus Cassida, or helmet beetle, eat the underside of the leaves of plants; frequenting, particularly, thistles, mint, &c., where they hide themselves under a cover of their own excrement supported in the air above their bodies, by means of the two prongs at the extremity of the tail. When this artificial umbrella becomes too dry, they cast it off, and form a new one. It is very small, of an oval figure; the colour of its back bright green, and the under part coal-black. Among the pretty insects of the next genus, Coccinella, you will find the gay tribe of Lady-birds, which have even escaped the sad prejudices of our nation as regards insects, so that children caress these handsome and most useful creatures in England, and in Ireland they are equally esteemed, being called the cows of God. There are upwards of thirty different species, some are scarlet with black spots, others yellow with black, or black with red, or yellow with white spots. It seems, however, that many persons are unacquainted with the early stages of their existence; and as this has led to the fatal error of destroying the larvæ, which are amongst the most valuable aids the cultivator has, in keeping under the aphides, it becomes very important that the gardener should be at once enabled to distinguish his friends from his enemies. If we examine the underside of the leaves of cinerarias or any plants when they are greatly infested with plant-lice (aphides), we shall find little clusters of orange or buffcoloured eggs, deposited close together on their ends, and very much resembling those of the white cabbage-butterflies at the first glance, but they are very different when magnified; they are more elliptical, fleshy, and smooth, not being sculptured as those of the papilios are. The first brood hatches in May, when the pearly empty shells alone remain, and the little black animals issuing from them, run over the leaves in search of food, at this time they are rough with hairs, and have six short strong legs; as they grow they change their skins and eventually those of the largest species attain the length of five or six lines; the larva now has a slate-coloured skin, smooth, but dull, the body is attenuated towards the apex, and extends far beyond the six black sprawling legs, so that it looks like a little alligator, which it likewise resembles in its voracious and carniverous habits. The ladybirds are probably to be found the whole year, as they winter under bark, in chinks of posts, palings, &c., and are seen in the earliest days of spring, if the weather be fine, and late in the autumn also. Immense numbers are generally to be seen in the hop grounds in Kent, where their good services are gratefully acknowledged by the farmers. The vast quantities of aphides which the larvæ of the lady-birds destroy cannot be calculated, for they seem never to cease from feeding, except when they are moulting, and the lady-birds themselves are equally active, one sees these pretty scarlet animals running over the plants until they meet with an aphis which they immediately seize with their broad feelers, and keep squeezing out the saccharine contents until the crumpled skin alone remains; they then attack another and will thus proceed, until leaf by leaf the plant is freed from this disagreeable and destructive blight. A Table Showing the number of trees or plants required for an acre of ground from one foot to twenty-one feet distance. The solution of the question is simple when we consider that there are 6 272 640 square inches in an acre. On reference to page 38 will find there are by by you 4 840 square yards in an acre multiplied 43 560 multiplied 144 the number of square inches in a foot. 174 240 174 240 43 560 6 272 640 the number of square inches in an acre. When the multiplicand and multiplier are the same, that is when the number is multiplied by itself once, the product is called the square of that number, 144 as on the other side is the square of twelve inches or one foot. Distance. Ft. in. Plants. Distance. Plants. Distance. Plants. Distance. Plants. Ft. in. 193 Ft. in. Ft. in. 6 = 602 15 = 0 = 1,742 9 6 = 1,440 9 0 = 1,210 10 6 = 1,031 11 0 = 120 108 98 Example 1. Required the number of trees to plant an acre at eighteen inches from tree to tree. 18 18 144 18 324) 6272 640 (19360 trees. 324 3032 2916 1166 972 1944 1944 Example 2. Required the number of trees to plant an acre seven feet six inches from tree to tree. 7.6 90 90 8 100) 6 272 640 (774 trees. Ex. 3. How many cabbage plants will stand upon an acre at the distance of nine inches from plant to plant. Son. Dear sir, we are anxious to hear your account of what you call the secondary constituents of climate. John (the foreman) and I have been talking the subject over, but we could not clearly comprehend the various influences by which a climate may be produced. Mr. B. I am glad that you have discussed the subject among yourselves, as it is by talking over the lessons which you hear that they will make a deeper and more lasting impression on the mind, and any doubts or difficulties which may present themselves, if referred to me, I shall endeavour, to the best of my ability, to clear up. But, before I enter upon the fulfilment of my promise, it is necessary, as our globe is the subject of our discourse this evening, to make you acquainted with its annual and diurnal motions. K Astronomers, for the convenience of their science, have supposed certain lines to pass through and around the globe. One, passing through the centre, between north and south, is called the axis of the globe, from a Greek word signifying axle. The two extremities are called the poles, from the Greek word polos, signifying a pivot. A line girding the globe in the middle is styled the equator; all to the north and south of which are respectively called the northern and southern hemisphere. The circuit of the earth, both in its girth between east and west, and between north and south, is divided into 360 parts called degrees. At the distance of twenty-three and a half nearly of these degrees from the equator, in both directions, are two parallel lines called the tropics; and at the same distance from each pole is a parallel circle, the one in the north is styled the arctic and in the south the antarctic circle. The space between the tropics is called the torrid zone, because the sun, being always vertical in some part of that space, produces a greater degree of heat than what is felt elsewhere. The spaces between the tropics and the arctic and antarctic circles are called the temperate, and the spaces within the arctic and antarctic circles the frigid zones. Lastly, a line which cuts the equator obliquely, touching upon opposite points of the tropics, is called the ecliptic. The ecliptic and equator are called greater circles, because they cut the earth at the thickest parts—the others are called lesser circles. A series of lines drawn from pole to pole over the earth's surface (like the division lines of a peeled orange), and cutting the equator at right angles, are called meridians (from the Latin word meridies, midday) or lines of longitude. Every place upon the earth is supposed to have one of these passing through it, although only twentyfour are described upon the terrestrial globe. When any one of these is opposite the sun, it is then midday or twelve o'clock with all the places situated on that meridian, and, consequently, midnight with those on the opposite meridian on the other side of the earth. The exact situation of a place upon the earth's surface, or its latitude or longitude, is determined by means of these circles. They are all divided, as already hinted, into 360 parts, which parts are called degrees, these degrees again into 60 equal parts called minutes, the minutes into 60 others called seconds, and so on. They are all indicated by certain signs placed behind the figure and near the top of it, thus-7° 6' 4", is 7 degees, 6 minutes, 4 seconds. A degree is 60 geographical miles, or about 69 English statute miles. The latitude of a place is its distance measured in that manner from the equator. If it lies north of that line, it is in north latitude; if south of it, |