Practical Mechanics for Boys | Page 3

59. Belt lacing 69 60. Belt lacing 69 61. Belt lacing 69 62. Bevel gears 71 63. Miter gears 71 64. Crown wheel 71 65. Grooved friction gears 71 66. Valve 71 67. Cone pulleys 71 68. Universal joint 71 69. Trammel 73 70. Escapement 73 71. Device for holding wheel 73 72. Rack and pinion 73 73. Mutilated gears 73 74. Shaft coupling 73 75. Clutches 75 76. Ball and socket joints 75 77. Fastening ball 75 78. Tripping devices 75 79. Anchor bolt 75 80. Lazy tongs 75 81. Disc shears 75 82. Wabble saw 76 83. Continuous crank motion 76 84. Continues feed 76 85. Crank motion 76 86. Ratchet head 76 87. Bench clamp 76 88. Helico-volute spring 77 89. Double helico-volute 77 90. Helical spring 77 91. Single volute-helix 77 92. Flat spiral or convolute 77 93. Eccentric rod or strap 77 94. Anti dead-centers for lathes 77 95. Plain circle 95 96. Ring 96 97. Raised surface 96 98. Sphere 96 99. Depressed surface 96 100. Concave 97 101. Forms of cubical outlines 98 102. Forms of cubical outlines 98 103. Forms of cubical outlines 98 104. Forms of cubical outlines 98 105. Shading edges 99 106. Shading edges 99 107. Illustrating heavy lines 100 108. Illustrating heavy lines 100 109. Lines on plain surfaces 101 110. Lines on plain surfaces 101 111. Illustrating degrees 102 112. Section lining 103 113. Drawing an ellipse 104 114. Perspective at angles 106 115. Perspective of cube 107 116. Perspective of cube 107 117. Perspective of cube 107 118. Protractor 108 119. Using the protractor 109 120. Section-lining metals 110 121. Spur gears 122 122. Miter gear pitch 123 123. Bevel gears 124 124. Laying of miter gears 125 125. Sprocket wheel 128 126. Simple lever 129 127. Lever action 130 128. The pulley 132 129. Change of direction 133 130. Change of direction 133 131. Steam pressure 135 132. Water pressure 135 133. Prony brake 141 134. Speed indicator 142

PRACTICAL MECHANICS FOR BOYS

INTRODUCTORY
The American method of teaching the mechanical arts has some disadvantages, as compared with the apprentice system followed in England, and very largely on the continent.
It is too often the case that here a boy or a young man begins work in a machine shop, not for the avowed purpose of learning the trade, but simply as a helper, with no other object in view than to get his weekly wages.
Abroad, the plan is one which, for various reasons, could not be tolerated here. There he is bound for a certain term of years, and with the prime object of teaching him to become an artisan. More often than otherwise he pays for this privilege, and he knows it is incumbent on him "to make good" right from the start.
He labors under the disadvantage, however, that he has a certain tenure, and in that course he is not pushed forward from one step to the next on account of any merit of his own. His advancement is fixed by the time he has put in at each part of the work, and thus no note is taken of his individuality.
Here the boy rises step after step by virtue of his own qualifications, and we recognize that one boy has the capacity to learn faster than another. If he can learn in one year what it requires three in another to acquire, in order to do it as perfectly, it is an injury to the apt workman to be held back and deterred from making his way upwardly.
It may be urged that the apprentice system instills thoroughness. This may be true; but it also does another thing: It makes the man a mere machine. The true workman is a thinker. He is ever on the alert to find easier, quicker and more efficient means for doing certain work.
What is called "Efficiency" in labor methods, can never obtain in an apprenticeship system for this reason. In a certain operation, where twelve motions are required to do a certain thing, and a minute to perform the twelve operations, a simplified way, necessitating only eight motions, means a difference in saving one-third of the time. The nineteen hundred fewer particular movements in a day's work, being a less strain on the operator, both physically and mentally, to say nothing whatever of the advantages which the proprietor of the shop would gain.
I make this a leading text in the presentation of this book; namely, that individual merit and stimulus is something of such extreme importance that it should be made the keynote for every boy who tries to become a mechanic.
The machinist easily occupies a leading place in the multitude of trades and occupations. There is hardly an article of use but comes to the market through his hands.