SCIENTIFIC DIALOGUE, NOT BY MR. JOYCE.

Intelligent Pupil—What curious-looking pnwderl It is highly granulated, has a Banish taste, and is sold, I perceive, at the chandler's shop; whence I infer that it is useful as food. Tutor—By no means. Its uses are very different.

Pupil—Will you explain them?

Tutor—The value of this powder is derived from a property which it has of suddenly expanding into a much larger volume. It is evident that if you heat this powder in a confined space it mast have a vent for its own expansion; and in seeking that vent, it will tear apart the strongest bodies. In this way it is used for blasting rocks.

Intelligent Pupil—From that useful property, I suppose it is named blasting-powder.

Tutor—By no means; it is called gunpowder, from another ingenious ap- plication of its chemical properties.

Dull Pupil—Is that a marble which you hold in your hand?

Tutor—Your question, my dear boy, is not unnatural, though it is founded on an erroneous generalization of imperfect premises. You will observe that this substance is of a different colour from any marble, softer, and heavier. By an ingenious arrangement, the expansive powder is placed in a chamber of very confined spaoe, which opens at one side into a tube; this rounded metal or bullet exactly fits that tube, and by the help of an intervening body called wadding, it forms the wall of the chamber contain- ing the expansive powder. Now it is evident that if you apply heat to the expansive powder, which is done through a small hole, its expansion will cause it to displace both the wadding and the bullet, which are driven with incredible velocity along the tube, and indeed much beyond it, into the air.

Intelligent Pupil—You interest me greatly. But what is the use of this tubular projection of the spherical piece of lead?

Tutor—Patience! The extreme rapidity of its career imparts to the bullet a momentum equal to many pounds' weight on the area of its sec- tion; insomuch that it is capable of wholly overcoming that attraction of cohesion between the particles of solid bodies which holds them together.

Intelligent Pupil—I perceive; it breaks or smashes them.

Tutor—Exactly so; and it is found that when a bullet thus propelled encounters a living organic substance, the result is very painful, if not fatal.

Intelligent Pupil—I presume, then, that the experimental philosophers who employ this tubular apparatus always take care to avoid a line of motion perpendicular to the surface of any organized substance?

Tutor—Your presumption, however, is not justified by the facts: on the contrary, the tube or gun is often so directed as to come across the organic substances, not excepting man himself.

Dull Pupil—But is not that very wicked, Sir?

Tutor—Ask the Duke of Wellington, when next he dines with your papa.

Intelligent Pupil—Ahl I see; you are describing war.

Tutor—I am. But sometimes the same properties of this expansive matter are applied in a mode that does not properly come under the head of war. What is this?

Pupil—It is a man.

Tutor—Da you note anything particular about him? Pupil—It is a remarkably well-grown mac; he-seems to me to have all his limbs-well made, his senses complete; and, jiidging by his pulse, I should say that he is a human being of strong sensationaamtatrong feel- ings. I perceive that he wears an orange-coloured scarf.- Tutor—Right: it is an Irish Orangeman. This day is the lath of July, and he puts on that scarf to commemorate the battle of the Boyne; a re- collection very disagreeable to the large number of Roman Catholics whom you see around.

Dull Pupil—How very bullying and illnatured! What is he going to do? Tutor—He is going to march through that pass, because the Ribandmen dislike him to do so.

Dull Pupil—Is there no other way, then?

Tutor—There is another and a better way; but you will perceive that the pass is not unoccupied.

Intelligent Pupil—True, it is filled with men wearing green scarves; and I perceive that they bear the tubular apparatus for the rapid impulsion of leaden spheroids. Tutor—Now if you watch, you will perceive the Orangeman, who is similarly armed, go round through that pass, and so bring the organized substance of his body within the range of those tubes; heat will be applied to the expansive powder, the leaden ball will be propelled, it will encoun- ter the Orange substance, with the remarkable result of making a round hole; and should that bole pass through a vital portion of the Orange or- ganism, the man will die.

Intelligent Pupil—I observe bodies of men whom I take for Queen's sol- diers and policemen, and I presume that they will be authorized to prevent so very dangerous an experiment in explosive forces. Tutor—Undoubtedly; but not before the nature of the experiment has developed itself. The bystanders are presumed not to know what is going to happen. Dull Pupil—How very stupid it is of the Orangeman not to go the other way! Teeter—My dear boy, when you are a little older you will understand that he does so to uphold theeprinciples of Protestant ascendancy. Dull Pupil—What! by inviting the disintegration of his organic sub- stance?

Tutor (smiling)—Not exactly; the Orangeman, you perceive, also carries a tube or gun. Dull Pupil—Ah: then he can shoot Protestant principles into a Catholic, as you squirt water over flowers from the garden-engine, to make theta grow.

Tutor—Your simile is not inapt. Intelligent Pupil— Unfortunately, if the Roman Catholic's heart is reached, he will die in the very process. Tutor—The remark is just. But we are not now considering how We should act.

Dull Pupil—One question more, Sir: What is gained by this application of explosive forces to the religious differences of the native Irish, that it should receive the tacit sanction or at least sufferance of Government. until, as you say, the experiment has been in some degree developed? Tutor—That is a very interesting inquiry; but I believe the results have not been ascertained. Here, if you please, we will close our glance at the natural history of Ireland: in which, however brief it May have been, I have shown you the most common application of practibal science

country; the tubular apparatus or gun being almost the only scientific hie strument familiar to the poor Irieb. in that