and among all the properties of matter that of weight is the most universal; secondly, because their life is spent in details, and the tendency of details is to narrow the mind. The practical man is always tempted to attach too much importance to local experience, to peculiar circumstances with which he has had to cope, and to his own contrivances for mastering his special difficulties. One great means of correcting these tendencies is to acquire a confidence in the laws of nature, and to know the inevitable conditions of work and of power. The kind of practical confidence which I mean is gained, under the law of labour, by the workman, and his remarks often surprise amateurs who have never put their own hands to the spade. This subject may be illustrated by the remark of an intelligent Exeter tradesman, with which 1 was much struck. Speaking of pottery-works, he said, "It takes six tons of coal to burn one ton of clay; so it is cheaper to carry the clay to the coal than the coal to the clay." How many unprofitable speculations would have been averted by the habit of applying plain laws of nature to business in this way.
I may mention two facts of an opposite character. I was once pitching hay with my boys in the field of an excellent farmer, now no more; and each of us trying to lift as much as we could, I dropped my right hand close to the load to give it the first lift more easily, and advised my boys to do the same. I observed the farmer did otherwise, holding both hands comparatively near the other end of the fork. As I am always in the habit of attending to the experience of practical men, I asked him if I was wrong? He told me I was, and gave me, as a reason, that, in turning the screw of a cider-press, you put your hand as near the end of the lever as possible. Whether he was right in the fact I will not now discuss; but no one who has ever been trained in the first principles of mechanics would have given such a reason.
Another instance of practical error, arising from inattention to a simple law of mechanics, was a recommendation I once heard given to increase the purchase of a wheel and axle by lengthening the axle; and the reason given was the increase of purchase gained by using a long screwdriver. The facts are trifling, but they show the bearing of sound mechanical principles on practical business.
Chemistry and Physical Science.
Next to natural philosophy, in order of direct reference to business, should naturally come chemistry. As a means of opening the mind and creating an interest in the powers of nature and the processes of art, chemistry is certainly most valuable. Under the direction of a competent chemist the practice
