Mechanical skill

“ As users of these tools we cannot begin to compare with the skilled workman of ancient days. Our progress is shown not in the development of skill, but in the loss of it. We have taken the tool out of the human hand and put it into an inanimate machine. It is only very recently that the tool was delivered to the machine and that act marked the dawn of the present remarkable mechanical era. ”

“ The improvement so much to be desired, will speedily follow upon the discontinuance of grinding. Recourse must then be had to the natural process. The surface plate and the scraping instrument will come into constant use, affording the certain and speedy means of attaining any degree of truth which may be required. A higher standard of excellence will be gradually established, the influence of which will be felt throughout all mechanical operations, while, to the mechanic himself, a new field will be open, in which he will find ample scope for the exercise of skill, both manual and mental. ”

“ That Skill in mechanical contrivance is a matter of education and training as well as of inborn faculty, is clear from the fact of so many of our distinguished mechanics undergoing the same kind of practical discipline, and perhaps still more so from the circumstance of so many of them passing through the same workshops. Thus Maudslay and Clement were trained in the workshops of Bramah; and Roberts, Whitworth, Nasmyth, and others, were trained in those of Maudslay. ”

“ In fact, physics teaches us that the hand is a combination of the six mechanical powers--the lever, the wedge, the wheel and axle, the pulley, the screw, and the inclined plane. But the mechanical effect is always depreciated. ”

“ The study of kinematics has been considered for nearly 80 years as a necessary part of the mechanical engineer's training, as the dozens of textbooks that have been published over the years make amply clear. ”

“ The study of motors and motive power is one which calls for the highest engineering qualities. In this, as in every other of the mechanical arts, theory, while it has an important function, occupies second place. ”

“ For from hence are easily deduced the forces of machines, which are compounded of wheels, pullies, levers, cords, and weights, ascending directly or obliquely, and other mechanical powers; as also the force of the tendons to move the bones of animals. ”

“ In the selection of the subjects, the question of practical utility has in many cases been regarded as the one of paramount importance. The elementary truths of Mechanics are too well known to admit of novelty, but it is believed that the mode of treatment which is adopted is more or less original. This is especially the case in the Lectures relating to friction, to the mechanical powers, to the strength of timber and structures, to the laws of motion, and to the pendulum. The illustrations, drawn from the apparatus, are nearly all original, and are beautifully executed. ”

“ How to Experiment with Machines.—Any one who possesses the slightest bent for mechanics can work out improvements on devices like egg-beaters and monkey-wrenches and feel their way as they go along.
But when it comes to designing and building real machines where numerous levers, gears, and springs are combined to make a working unit you should by all means read up on the subjects of work, energy and power, learn about the six mechanical powers—and the action of machines in general. ”

“ The man who aspires to construct any great mechanical engineering work, like the Brooklyn Bridge, for example, must know the exact mechanical power of every piece of machinery he employs, as also the exact mechanical value of every piece of iron that enters into the structure; and these things he cannot know unless he is familiar with the entire series of iron manipulations, from those of the foundery to those of the machine-tool shop. ”

“ It would be absurd to deny all recognition or knowledge of mechanical causation to people who show so much ingenuity in the construction of houses, boats, weapons, and a great variety of mechanical devices, such as traps, and in other operations involving the intelligent application of mechanical principles. ”

“ The lever, the pulley, the wheel and axle, the inclined plane, the wedge and the screw; one or more of which enters into the composition of every machine.
A mechanical power is an instrument by which the effect of a given force is increased, whilst the force remains the same.
In order to understand the power of a machine, there are four things to be considered. 1st. The power that acts: this consists in the effort of men or horses, of weights, springs, steam, &c.
2dly. The resistance which is to be overcome by the power: this is generally a weight to be moved. ”

“ Mechanics are still living who firmly believe in the possibility of realizing a mechanical perpetual motion,—to spin, pump, or drive carriages or machinery, by means of a constantly descending weight. ”

“ Those interested in mechanics will discover for themselves the mechanical defects and unnecessary complications introduced into them. I was working under the supervision of fairly good mechanical engineers, so that defects might not be made too glaring. ”

“ It must be admitted, too, that the sense of the reality of this separation has been felt not only by Engineers or others actually engaged in machine design, but also by those theoretical writers who have had any practical knowledge of machinery, in spite of the increasing tendency in the treatment of mechanical science to thin away machine-problems into those of pure mechanics. ”

“ Action and reaction being equal, the power exerted in raising or moving one heavy body must be exerted reversely against the earth, or other fixed body serving as a fulcrum to the lever, or for the attachment of one extremity of a tackle or series of pullies, or for the securing of the capstan spindle. Let the attachments of the machine and its object, however, be both afloat, and then any of the mechanical powers, like that of the wedge, will have an efficiency of double that of its ordinary operation where one part is a fixture. ”

“ In following the course of invention and rediscovery during the middle ages, and in subsequent times, we see two main causes of the superiority of our own useful arts to those of the ancients—the extended application of mechanical and chemical science. The discovery of the various problems in mechanics, which paved the way for the multiplication of human force, and the introduction of new motor powers, occupied chiefly the latter half of the sixteenth and the seventeenth century. ”

“ The story of machinery, from primitive man’s first attempts to augment his physical powers with mechanical aids down to the present era of gigantic, steel-muscled machinery and marvelously intricate mechanisms, is the story of human progress. ”

“ The force exercised by the human hand in lifting a weight either with or without rope and pulley is, in every definitional sense of the word, mechanical force. For the arm and hand are only the implements, or mechanical contrivances of nature, by which the will-power transmutes itself into work, or, more properly speaking, transmits itself from the point of force-generation to that of force-expenditure. And this is precisely the office performed by all mechanical contrivances for the transmission--not transmutation--of force. ”

“ As, however, the actual machinery itself, deriving its existence from various sources, and having its own characteristic features and methods of classification and treatment, forms a quite distinct and special subject, a separation of its scientific mechanical problems from those of Mechanics in general is possible, and indeed has already been made. ”

“ Being self-taught, but with some little ambition, and a determination to improve himself, he was now enabled to stand before them with some pretensions to mechanical knowledge, and the persuasion that he had been a useful contributor to practical science and objects connected with mechanical engineering. ”

“ Sometimes they connect a moving wheel with the piston used in churning. In another place you see a cradle rocked with a motion the more gentle as it is produced by a fall of water moderated [Pg 40] with art. In short, a stranger who visits their country, perceives, at every step, the extraordinary turn of these people for the mechanical arts. ”

“ Yet this remarkable contrivance, with all its massive steel beams and chains and cog wheels, employs no other principles than the simple ones of lever and pulley and inclined plane that we have just examined. The power that must be applied to produce a given effect may be calculated to a nicety. The capacities of the machine are fully predetermined in advance of its actual construction. But of course this is equally true of every other form of power-transmitter with which the modern mechanical engineer has to deal. ”

“ The machine tools did all the working (for the thinking had been embodied in them beforehand) , and they turned out all manner of geometrical forms with the utmost correctness. This sort of training educated the faculties of the lads, and trained their ideas to the perception of exactness of form, at the same time that it gave them an intimate acquaintance with the nature of the materials employed in mechanical structures. The rapidity with which they thus acquired the efficiency of thoroughly practical mechanics was surprising. ”

“ We see this very clearly in the names of the different parts of machinery, which are taken from the names of similar parts in the human frame. Almost every member of the body is used in mechanical terminology. ”

“ Mechanical engineering, as we understand it, could only fairly start in its wonderful progress after the mechanic had found ways of utilizing natural forces and energies, and of making the tools with which to produce these prime motors, through the operation of which all the arts could be given application in the production of wealth, multiplying the power of the unaided hand by making it in the performance of work the guide of greater powers, rather than the tool itself. ”

“ A.--The mechanical powers are certain contrivances, such as the wedge, the screw, the inclined plane, and other elementary machines, which convert a small force acting through a great space into a great force acting through a small space. ”

“ But another conclusion follows more irresistibly, namely—that the mechanical engineer who devotes his attention to the construction and management of massive machinery, such as pumps, hydraulic and lever presses, looms, and steam-engines, whether locomotive, marine, or other, must, in order to be master of his profession, be thoroughly familiar with every step of their construction; and such familiarity can only be acquired by a course of practical study in the machine-tool shop. ”

“ In any machine, constructed in whatever manner to increase the force which I can exert, it is certain that what I gain in force I must lose in the velocity which I communicate. This is not a contingent truth, borrowed from and limited by observation; for a man of sound mechanical views applies it with like confidence, however novel be the construction of the machine. ”

“ Few mechanics have any distinct knowledge of the method to be pursued for obtaining it, nor do practical men sufficiently advert, either to the immense importance, or to the comparative facility of the acquisition. ”

“ This shows within what distinct limits machine-problems lie, and that they allow themselves to be readily separated from the general problems of Mechanics, as we have already maintained.
While the science of Mechanics examines motion caused in the most general cases by the action of mechanical forces, Machine-mechanics occupies itself with certain special cases only, with motions produced by a limited circle of means. It draws its first laws from the same fountain as Mechanics, to which, as the more comprehensive science, it is subordinate. ”

“ As soon as a boy begins to take an interest in moving parts of machinery, vehicles, locomotives, and what not, he perceives that the application of power results in the motion of bodies, and again that bodies in motion are productive of power. A wheel moved by muscular, or other mechanical power, is made by machinery to elevate water, and elevated water can be made in descending to run machinery. The windlass, or other12 wheel, turned by applied force, lifts buckets from wells—raises stone, and elevates heavy bodies, if desired. ”

“ Workingmen of our day should ponder over this, and take to heart the truth that manual mechanical labor is the likeliest career to develop mechanical inventors and lead them to such distinction as these benefactors of man achieved. ”

“ He who would accomplish most in the profession of the mechanical engineer must best combine scientific attainments—and especially experimental knowledge—with mechanical taste and ability and a good judgment refined by engineering experience. ”

“ If he goes further and analyzes the reasons for this impression of power, he will see that it is not merely a mental suggestion, but a realization of the actual existence of tremendous mechanical power, under complete direction and control.
In mechanics we get a definition of power, which, like all definitions in mechanics, is clear, definite, and correct. ”

“ It was, also, not difficult for a person with clear mechanical ideas to perceive how any other combination of bodies, on which pressure and traction are exerted, may be reduced to these simple machines, so as to disclose the relation of the forces. ”

“ Mechanical Advantage.—A lever often gives an advantage because by its use one may lift a stone or weight which the unaided strength of man could not move. If the lever is used in lifting a stone weighing 500 lbs., the force available being only 100 lbs., then its mechanical advantage would be 5, the ratio of w:f. In a similar way, the mechanical advantage of any machine is found by finding the ratio of the resistance or weight to the effort. ”