FORE:A few years ago, or even at the present time, many school-books in use which treat of mechanics in connection with natural philosophy are so arranged as to hinder a learner from grasping a true conception of force, power, and motion; these elements were confounded with various agents of transmission, such as wheels, wedges, levers, screws, and so on. A learner was taught to call these things "mechanical powers," whatever that may mean, and to compute their power as mechanical elements. In this manner was fixed in the mind, as many can bear witness, an erroneous conception of the relations between power and the means for its transmission; the two things were confounded together, so that years, and often a lifetime, has not served to get rid of the idea of power and mechanism being the same. To such teaching can be traced nearly all the crude ideas of mechanics so often met with among those well informed in other matters. In the great change from empirical rules to proved constants, from special and experimental knowledge to the application of science [4] in the mechanic arts, we may, however, go too far. The incentives to substitute general for special knowledge are so many, that it may lead us to forget or underrate that part which cannot come within general rules.Punctuality costs nothing, and buys a great deal; a learner who reaches the shop a quarter of an hour before starting time, and spends that time in looking about, manifests thereby an interest in the work, and avails himself of an important privilege, one of the most effectual in gaining shop knowledge. Ten minutes spent in walking about, noting the changes wrought in the work from day to day, furnishes constant material for thought, and acquaints a learner with many things which would otherwise escape attention. It requires, however, no little care and discrimination to avoid a kind of resentment which workmen feel in having their work examined, especially if they have met with an accident or made a mistake, and when such inspection is thought to be [168] prompted by curiosity only. The better plan in such cases is to ask permission to examine work in such a way that no one will hear the request except the person addressed; such an application generally will secure both consent and explanation.
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