he might try whether any person present could invent it. Mr. E thus stated the difficulty: "In the old steam " engine, cold water, you know, is thrown into the cylin" der to condense the steam; but in condensing the steam, "the cold water at the same time cools the cylinder. "Now the cylinder must be heated again, before it can " be filled with steam; for till it is heated, it will con" dense the steam. There is, consequently, a great waste " of heat and fuel in the great cylinder. How can you " condense the steam without cooling the cylinder ?"

S. "Let down a cold tin tube into the cylinder "when you want to condense the steam, and draw it up "again as soon as the steam is condensed; or, if you " could put a cylinder of ice up the great tube."

Some of the company next asked, if an horizontal plate of cold metal, made to slide up the inside of the cylinder, would condense the steam. The edges of the plate only would touch the cylinder; the surface of the plate might condense the steam.

"But," said Mr.

"withdraw it?"

" how can you introduce and

C (a girl of 12) then said, "I would put a cold " vessel to condense the steam at the top of the cylin"der."

Mr.-. "So as to touch the cylinder, do you mean?" C. "No, not so as to touch the cylinder, but at

"some distance from it."

Mr.-. "Then the cold air would rush into the " cylinder whilst the steam was passing from the cylinder " to your condenser."

C.

"But I would cover in the cold vessel, and " I would cover in the passage to it."

Mr.. "I have the pleasure of informing you, " that you have invented part of the great Mr. Watt's im"provement on the steam engine. You see how it facili

"tates

"tates invention, to begin by stating the difficulty clear"ly to the mind. This is what every practical inventor "does when he invents in mechanics."

L- (smiling.) "And what I always do in invent" ing a mathematical demonstration."

To the good natured reader we need offer no apology; to the ill natured we dare attempt none, for introducing these detailed views of the first attempts of young invention. They are not exhibited as models, either to do honor to the tutor or his pupils; but simply to shew, how the mind may be led from the easiest steps, to what are supposed to be difficult in education. By imagining ourselves to be in the same situation with children, we may guess what things are difficult to them; and if we can recollect the course of our own minds in acquiring knowledge, or in inventing, we may by retracing the same steps instruct others. The order that is frequently followed by authors, in the division and subdivision of their elementary treatises, is not always the best for those who are to learn. Such authors are usually more intent upon proving to the learned that they understand their subject, than upon communicating their knowledge to the ignorant. Parents and tutors must, therefore, supply familiar oral instruction, and those simple, but essential explanations, which books disdain, or neglect to give. And there is this advantage in all instruction given in conversation, that it can be made interesting by a thousand little circumstances, which are below the dignity of didactic writers. Gradually we may proceed from simple to more complicated contrivances. The invention of experiments to determine a theory, or to ascertain the truth of an assertion, must be particularly useful to the understanding. Any person, who has attended to experiments in chemistry and natural philosophy, must know, that invention can be as fully and elegantly displayed upon these subjects as up

on

on any in the fine arts or literature. There is one great advantage in scientific invention; it is not dependent upon capricious taste for its reward. The beauty and elegance of a poem may be disputed by a thousand amateurs; there can be but one opinion about the truth of a discovery in science.

Independent of all ambition, there is considerable pleasure in the pursuit of experimental knowledge. Children especially, before they are yet fools to fame, enjoy this substantial pleasure. Nor are we to suppose that children have not capacities for such pursuits; they are peculiarly suited to their capacity. They love to see experiments tried, and to try them. They shew this disposition not only wherever they are encouraged, but wherever they are permitted to shew it; and if we compare their method of reasoning with the reasonings of the learned, we shall sometimes be surprised. They have no prejudices, therefore they have the complete use of all their senses; they have few ideas, but those few are distinct; they can be analysed and compared with ease; children, therefore, judge and invent better, in proportion to their knowledge, than most grown up people.

Doctor Hooke observes, that a sensible man, in solving any philosophical problem, should always lean to that side which is opposite to his favorite taste. A chemist is disposed to account for every thing by chemical means; a geometrician is inclined to solve every problem geometrically; and a mechanic accounts for all the phænomena of nature by the laws of mechanism. This undue bias upon the minds of ingenious people, has frequently rendered their talents less useful to mankind. It is the duty of those who educate ingenious children, to guard against this species of scientific insanity.

There are prejudices of another description, which are fatal to inventive genius; some of these are usually found

to

to attend ignorance, and others sometimes adhere to the learned. Ignorant people, if they possess any degree of invention, are so confidant in their own abilities, that they will not take the pains to enquire what others have thought or done; they disdain all general principles, and will rather scramble through some bye path of their own striking out, than condescend to be shewn the best road by the most enlightened guide. For this reason, self-taught geniuses, as they are called, seldom go beyond a certain point in their own education, and the praise we bestow upon their ingenuity is always accompanied with expressions of regret: "It is a pity that such a genius had not the ad"vantages of a good education."

The learned, on the contrary, who have been bred up in reverence for established opinions, and who have felt in many instances the advantage of general principles, are apt to adhere too pertinaciously to their theories, and hence they neglect or despise new observations. How long did the maxim, that nature abhors a vacuum, content the learned ! And how many discoveries were retarded by this single false principle! For a great number of years it was affirmed and believed, that all objects were seen by the intervention of visual rays, proceeding from the eye much in the same manner as we feel any object at a distance from us by the help of a stick.* Whilst this absurd analogy satisfied the mind, no discoveries were made in vision, none were attempted. A prepossession often misleads the industry of active genius. Doctor Hooke, in spite of the ridicule which he met with, was firm in his belief, that mankind would discover some method of sailing in the air. Balloons have justified his prediction; but all his own industry in trying experiments upon flying was wasted, because he persisted in following a false Vol. II. analogy

Aa

* Priestley on Vision, vol. i. p. 23.

analogy to the wings of birds. He made wings of various sorts; still he took it for granted that he must learn to fly by mechanical means: had he applied to chemistry, he might have succeeded. It is curious to observe, how nearly he once touched upon the discovery, and yet, misled by his prepossession, quitted his hold. He observed, that the air cells * of fishes are filled with air, which buoys them up in the water; and he supposes that this air is lighter than common air. Had he pursued this idea, he might have invented balloons; but he returned with fatal perseverance to his old theory of wings. From such facts, we may learn the power and danger of prejudice in the most ingenious minds; and we shall be careful to preserve our pupils early from its blind dominion.

The best preservation against the presumption to which ignorance is liable, and the best preservative against the self-sufficiency to which the learned are subject, is the habit of varying our studies and occupations. Those who have a general view of the whole map of human knowledge, perceive how many unexplored regions are yet to be cultivated by future industry; nor will they implicitly submit to the reports of ignorant voyagers. No imaginary pillars of Hercules, will bound their enterpriz

There is no presumption in believing, that much more is possible to science than ever human ingenuity has executed; therefore, young people should not be ridiculed for that sanguine temper which excites to great inventions. They should be ridiculed only when they imagine that they possess the means of doing things to which they are unequal. The fear of this deserved ridicule, will stimulate them to acquire knowledge, and will induce them to estimate cautiously their own powers before they hazard their reputation. We need not fear that this