Jones, come out here, and try to lift that cupboard. You can't move it? Well, place the end of this rod a little way under it; now put this little block of wood under the rod close up to the cupboard; press down the other end of the rod; be careful. You see, boys, the cupboard is now being tilted up. Have you ever seen men lifting heavy things in that way? Ans.-Yes, sir: I saw a man getting up the flagstones in that way. (Another boy)-I saw a grocer getting a large barrel of sugar into his shop in that way. Just so. Embery, you seem stronger than Jones; come here; put the iron under the cupboard as before. Now I will bring the block a little farther out away from the cupboard. Now try to lift it. What! can't you move it? Ans.-No, sir; I can't shift it; there is not enough handle. What do you mean by 'not enough handle'? Ans. (Embery) The distance from the block to my hand. is not enough. Very well, then alter it. Ah! don't overturn the cupboard. You see how easily he tilts it. Try to lift the cupboard without the rod. You can't do it. You see, therefore, what an advantage there is in using this rod; and what must you do to lift the weight the more easily? Ans.-Have a long handle. Very good. Now you say that the distance from the block to your hand is the handle: what do you call the distance from the block to the other end of the rod? You don't know? You want a name for it; well, I will give you one, and also names for the other parts of this simple machine. Here is the picture of such a rod, with the names of the parts written. The rod itself is called a 'lever;' the block is the 'fulcrum ;' the cupboard or whatever we want to lift we will call the 'weight;' the force you apply to lift it is the 'power;' the distance between the fulcrum and the power, which Embery called the handle, is the 'powerarm,' and that between the fulcrum and the weight is the weight-arm.' How much do you think that cupboard, with all the books and slates in it, weighs? Ans. More than a hundredweight. Yes; I should think about two. Embery, do you think you could lift two hundredweight? Ans.-No, sir ; not without that lever. (A boy)--He couldn't lift it with the lever at

6

(Embery)-No, because there was not enough handle. (Teacher)-Don't say handle. (Embery)The power-arm was not long enough. Just so. Do you think these boys pressed the lever downwards with a force of two hundredweight? Ans.-No, sir; much less. And can you tell me exactly how much less? Ans. It depends upon how long the power-arm is. How do you know that? Ans. From trying it, and from our common sense. Exactly so. Now we will carry our common sense a little farther, and after making a few experiments with this apparatus, find out the true or scientific relationship between the various parts of that mechanical power called the lever. Howell, you come here; place this lever on that fulcrum. (Fig. 1 is placed on V.) Balance it. You see the lever is marked so that you can easily find the centre. Do you know the name of that balancing point? (A boy)-The centre of gravity. (Another boy)-You said the centre of gravity was somewhere in the middle of the earth. Yes; so the centre of gravity of the earth is. other boy)-You said everything had a centre of gravity. And so it has. The centre of gravity of that lever is just about where Howell has balanced it. Now, Howell, put a four-pound weight on the lever, say three distances from the fulcrum. Hold up the lever.

(An

now.

Smith, take this two-pound weight; put it on the other arm; see where it just balances. (Smith)—It balances How far is it from the fulcrum? Ans.-Six distances. Cox, come and write that on the blackboard. Two pounds six distances from the fulcrum balances four pounds three distances.' Now take the weights off. Dedden, you come out; place this sixpound weight one distance from the fulcrum. Drayson, see where you have to put this two-pound weight in order to maintain equilibrium. Here it is, sir, three distances from the fulcrum. Very good. Cox, write that on the board. Six pounds one distance balances two pounds three distances.' Just so. Now all go to your places. Look, boys. I place eight pounds on the lever two distances from the fulcrum : tell me where I must put this two pounds in order to balance. Ans.-Eight distances. You are right. You see how exactly it balances. I will write that on the board. I want you all now to look upon the blackboard. Think carefully of what we have done. Tell me whether, in these experiments, the results show a likeness in any respect. Ans.-Yes, sir: it's all the same thing. What do you mean, Richards, by 'all the same thing'? Ans. (Richards)-The arm that is shortest has the greatest weight. Very good. (Another boy) The smallest weight is always on the longest Yes; but that is almost the same as Richards has said. (Another boy)—If you call the arm on the left the weight-arm, and the one on the right the power-arm, then the weight is just as much greater than the power as the power-arm is greater than the weight-arm. (Howell)-If you multiply the weight by the weight-arm, it always equals the power multiplied by the power-arm. That's capital, Howell. Come out here, and show the boys that what you say is true. (Howell comes out greatly delighted.) In the first experiment four times three is the same as six times two; in the second, six times one equals twice three; in the third, eight times two equals twice eight. Very good. Now I want to write out these four quantities as a proportion: you can, I know, easily tell me how to do it, as you have lately heard a good deal about ratio and proportion. Ans. (Smith.)— The power is to the weight as the weight-arm is to the power-arm. Just so. I will write that on the board. P W w.-a. p.-a.'

arm.

In our next lesson we will work out some sums from this proportion. You may take out your exercisebooks, and copy all that we have written on the black-board.

STANDARD II.—(dictated : two sets). A (1) 67,894 × 85. Ans. 5,770,990. (2) 40,016÷7. Ans. 5716-4. (3) 41,30234,067. Ans. 7235. B (1) 67,894 94. Ans. 6,382,036. (2) 40,016÷6. Ans. 6669 2. (3) 41,302-40,819. Ans. 483.

STANDARD III.

(1) If 198 nuts be divided equally among 7 boys and 11 girls, how many will each receive? Ans. 11.

STANDARD IV.

(1) Multiply nineteen pounds thirteen and eightpence halfpenny by 109. Ans. £2145 14s. 2d. (2) If a man's wages are 3s. 7d. a day, and a boy's Is. 3d. a day, how much will a farmer, who employs 8 men and 3 boys, pay per week of 6 days in wages? Ans. 9 14s. 6d. (3) Divide £18,907 4s. 10d. (given in words) by 84. Ans. £225 1s. 83d. – 64. (4) In 763,972 inches (words), how many miles, fur., yds., etc.? Ans. 12 m. o f. 101 yd. I ft. 4 in. (5) Subtract £12,907 17s. 6d. from £22,382 75. 10 d. (words). Ans. £9474 Ios. 3 d.

STANDARD V.

many

(1) If 147 yards cost £4 11s. 10ld, how yards can be bought for 8s. 1d.? Ans. 13. (2) 8 yds. 18 ft. 216 in. at £1 16s. a foot. Ans. £421 8s. 6d. (3) Make out this bill-3 lb. of tea at 2s. 9d., 14 lb. of sugar at 7 d., and 21 dozen eggs. at 1s. Id. a dozen. Ans. 1 os. 1d.

(13) In what lake does it rise?

(14) Through which counties does the Wye run? (15) Where is the Isle of Man ?

(16) What separates Anglesea from the next county?

(17) What is the county on the other side of Menai Strait ?

(18) Name the highest mountain in that county. (19) What town stands on the Dee?

(20) Name seaports on or near the Bristol Channel. (21) What strait joins the English Channel with the North Sea?

(22) Name a town on Cardigan Bay.

(23) On what river is Liverpool?

(24) Through what counties does the Thames flow? (25) What is Anglesea besides an island?

(26) What country is on the other side of the English Channel ?

STANDARDS IV. TO VI.

(1) What is another name for Tasmania?
(2) Name the parts of Australia.
(3) What are they called?

(4) What is the chief town in Victoria?

(5) What is the chief town in New South Wales? (6) Chief river in Australia?

(7) Between what lakes are the Falls of Niagara ? (8) What is the largest river in North America? (9) Name the strait between Tasmania and Australia.

(10) How many islands form New Zealand? (11) Name a town in New Zealand.

(12) What do we get from there?

(13) Why do people go there?

(14) What is the distance of Australia from England?

(15) What was Australia formerly called?

(16) Name some of our possessions on the west of Africa.

(17) Why not emigrate to that part?

(18) Name an island in the Pacific Ocean belonging to England.

(19) What do we get from Australia?

(20) Where is Canada ?

(21) How did we get it?

(22) When did we get it?

(23) Name the provinces in Canada.
(24) Name some towns in Canada.
(25) What is Nova Scotia ?

(26) Where is it?

(27) Name a seaport of Nova Scotia.

(28) Name some lakes in Canada.

(29) What group of islands are east of Australia?

(30) How many islands form New Zealand? Name them.

(31) What do we get from Mauritius?

(32) Where is it?

(33) Name an island east of Africa belonging to England.

(34) Name an island in the Atlantic belonging to England.

AS

Practical Lessons on Insect Eife.

BY THEODORE WOOD, M.E.S.,
Joint Author of 'The Field Naturalist's Handbook.'
No. XIII. THE HOMOPTERA.

S has already been mentioned in one of the earlier papers of this series, the Homoptera and the Heteroptera are often considered to form sub-orders only, being collectively known as Hemiptera. By those who follow this system they are respectively termed Hemiptera-Homoptera, and Hemiptera-Heteroptera. As, however, the distinguishing features of the two groups are very strongly marked, we will consider them as forming separate orders, to the first of which, the Homoptera, the present paper shall be devoted.

The Homoptera include a number of insects many of which appear to be totally dissimilar from one another, and it is not until we carefully examine the structural characteristics that we find them to possess any family resemblance. The distinguishing features of the order may be briefly summed up as follows.

In the first place, the structure of both the upper and the lower pairs of wings is of a similar nature, whence is derived the title of Homoptera,' a word signifying 'same-winged,' and therefore very appropriate. These wings are membranous, the upper pair being slightly longer than the lower, which they entirely conceal when the insect is at rest. They do not overlap, however, the sutural margins running parallel with one another, just as is the case with the elytra of the Coleoptera.

The body is very convex, causing the wings to assume a rather curious position when not in use. This attitude is not easily described, but may easily be seen by an examination of one of the 'frog-hoppers' which are so plentiful in all parts of the country.

The mouth is situated on the lower surface of the head, and is furnished with a beak, or proboscis, by means of which the juices of the plants upon which the insect feeds can be imbibed into the system. This proboscis is merely a modification of the mandibles and the maxillæ, which are considerably elongated, and enclosed in the labrum, which forms a kind of sheath for the whole.

In all these insects the pupa is active, and generally bears a considerable resemblance to the perfect insect, the chief distinction, of course, lying in the absence of wings.

There is yet another characteristic of the insects of this order, however, and that a very important one, for upon it is based the present arrangement of the group. This is found in the structure of the tarsi, which, in the Homoptera, are never found to consist of more than three joints. They may, however, have less, and Mr. Westwood has divided the insects of the order into three groups, namely, those which possess three joints in the tarsi, those which have two joints, and those in which one joint only is to be found.

The first of these groups is scientifically known as the Trimera, and is sub-divided into three families, of two only of which we have representatives in this country. In all the insects of this group the antennæ are very short, and are terminated by a slight bristle.

Of the first family, the Cicadida, we have only one

British representative, and that solitary exception is so rare that it is very seldom seen, even by working entomologists. This insect, the lower surface of which is represented in the accompanying woodcut, possesses no popular title, probably on account of its rarity, but is scientifically known as Cicada anglica.

Cicada anglica.

Many of the foreign cicadas, that is, as far as the males are concerned, possess the faculty of uttering a very loud and shrill cry, which is audible at a considerable distance. This sound is produced by a pair of tightly-stretched membranes found beneath the thorax, which are protected by a horny plate easily visible upon examination.

It has not as yet been ascertained whether our British cicada is musical or not, although the probabilities are that it is so. It is true that a specimen of the male insect was kept in captivity for a couple of days without being heard to utter a sound, but this period of time cannot be considered sufficiently long to warrant us in coming to any definite conclusion upon the subject. It is much to be hoped that the next person who is fortunate enough to meet with a male cicada will endeavour to set this mooted point at

rest.

The female cicada is furnished with an ovipositor of rather curious form, resembling a double spear with strongly serrated edges. By means of this instrument the insect is enabled to bore a hole in the substances in which her eggs are to be deposited.

The larva dwells in burrows in the earth, which it excavates by means of the very powerful fore-limbs. These tunnels sometimes extend to a considerable depth, some of the foreign cicadas sinking their habitations more than three feet into the ground.

The representation of the cicada which accompanies this description shows very clearly the peculiar form of the head, which is common to all the insects of the family to which it belongs, and also illustrates the manner in which the proboscis is packed away beneath the body when not required for use. The form of the body, too, is very well depicted, and, were it not for the size, the woodcut would serve as a very efficient illustration of the lower surface of almost any of our British Trimera.

Of the second family of this group, namely, the Fulgorida, or Lantern-flies, we have no British examples, and, as our space will not allow us to describe of the foreign homoptera, we must pass to the third and last family of the trimera, namely, the Cercopida.

any

These insects are more familiarly known by the title of 'Frog-hoppers,' as they are popularly termed when they have arrived at the perfect stage of their development, and by that of 'Cuckoo-spit,' by which they are generally known while yet in the larval condition.

There must be few, indeed, who have ever possessed the use of a garden, or enjoyed a country walk during

the summer months, who have not noticed the peculiar masses of frothy substance to be seen upon the stems of many plants, and which are frequently in such abundance as to completely drench the lower garments of the pedestrian.

This frothy secretion is popularly considered to be composed either of the saliva of the cuckoo or of that of the frog, to which notion are owing the popular titles both of the larva and the perfect insect. In reality, it is formed in a very singular manner.

Driving its beak into the skin of its food-plant, the grub extracts the juices which constitute its nourishment. When they have passed through the system, these juices are exuded in the form of the frothy substance with which we are so familiar, and which covers the entire body of the larva. At occasional intervals the bubbles of which this frothy mass consists resolve themselves again into a liquid form, a drop every now and then falling to the ground, while another slowly takes its place, following the first, after a time, in like

manner.

In the insects of this group the hinder limbs are formed for leaping, and are endowed with truly wonderful powers. It has been calculated that by their aid one of these Hoppers can leap to a distance equal to seventy times its own length; much the same as if a man were to spring over four hundred feet of ground at a single bound.

In order that they may be enabled to obtain a firm purchase upon the ground while preparing for these wonderful leaps, the hinder tibiæ are armed with a number of sharp spines, which afford the requisite foothold.

None of the insects of this division possess the curious sound-producing apparatus found in the cicadas.

The most striking insect of this group is the Scarlet Hopper (Cercopis sanguinolenta), which may occasion

Scarlet Hopper (Cercopis sanguinolenta).

ally be seen resting on the leaves of the common bracken upon a sunny morning in the early summer. It is a remarkably handsome creature, which, once seen, can by no possibility be mistaken, the bold scarlet and black markings at once pointing it out from amongst its congeners.

This is by no means a rare insect, although it is very local, so much so, indeed, that it is often found to be confined to a few square yards of ground. Easily detected, on account of its brilliant colouring, it is by no means so readily captured, making one of its tremendous bounds at the slightest sign of approaching danger, and being quickly lost to sight among the herbage.

Many other frog-hoppers are known to inhabit this country, but they are, as a rule, so plain and insignificant to ordinary examination, and so similar to one another in their habits, that there is no necessity for us to expend space upon their description.

We will therefore pass to the next group of the Homoptera, namely, the Dimera, or those in which two joints only are found in the tarsi. This division

includes the insects popularly known as Plant-lice, or Green Blight, and scientifically as Aphide, which are such terrible enemies to the horticulturist.

Aphis (Winged form).

These little insects are by no means formidable individually, but become so from the vast numbers in which they are found. They are wonderfully prolific, and that in a manner quite different from that which is customary with insects in general.

Aphis (Apterous form).

For, in these insects, the peculiar method of reproduction termed Parthenogenesis is strikingly exemplified. A female Aphis, kept entirely isolated from the other sex, will produce female young, and female young only, at the rate of fourteen or fifteen per diem, which, strange to say, pass through no preliminary stages of development, but are brought forth in a perfect condition, differing only in size from their parent. These in their turn give birth to a third generation, and so on. This strange method of reproduction has been known to extend over a space of several years, during the whole of which time no male aphis had been allowed access to the insects.

This will account for the wonderfully rapid rate at which the aphides increase, myriads appearing where only a few days previously not an example was to be seen. The birth of prolific females of course increases the reproductive powers to a wonderful extent, and there are few creatures which multiply with the extreme rapidity of the aphis.

Now and then the aphis does lay eggs, but this is the exception, and not the rule, the usual method of reproduction in this extraordinary insect being by the parthenogenesis above described.

Although individually an aphis can scarcely do any appreciable harm to a plant, the extraordinary numbers of the aphides render them a most terrible pest to agriculturists. There are few plants or trees to which some species of aphis does not attach itself, and which do not suffer very considerably from the ceaseless persecutions of its tiny foes.

The hop, especially, is a particular favourite with these little insects, and, were it not for the attacks of the ladybirds, the lacewing-fly, and many other insects which find in them their principal food, the cultivation of this plant would be an absolute impossibility. Gardeners, also, know only too well the ravages caused by the blight upon many of their favourite flowers, and vainly exhaust their energies in devising means to extirpate their destructive foes.

Yet, by a marvellous provision of nature, the enemies of the blight seem always to appear in proportion to the numbers of the pest. If our walls and windows are overrun with ladybirds, we may be sure that the