Self-help Mechanical Drawing: An Educational Treatise |
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Page 252
... rays from every visible part of the object are reflected , all following the same law , the reflection will appear ... Visual Rays . The human eye may be briefly described as a chamber 252 Hawkins ' Mechanical Drawing .
... rays from every visible part of the object are reflected , all following the same law , the reflection will appear ... Visual Rays . The human eye may be briefly described as a chamber 252 Hawkins ' Mechanical Drawing .
Page 253
... eye may be briefly described as a chamber of a spherical or globular form , with a circu- lar opening in front . This circular opening is called the pupil , and through it the visual rays pass to the interior of the eye . The visual rays ...
... eye may be briefly described as a chamber of a spherical or globular form , with a circu- lar opening in front . This circular opening is called the pupil , and through it the visual rays pass to the interior of the eye . The visual rays ...
Page 254
... eye . In fig . 305 we have a rough sectional diagram of the eye and an object in front of it . This object , an arrow , is seen by means of the visual rays proceeding from it , the principal two of which are shown . The visual ray from ...
... eye . In fig . 305 we have a rough sectional diagram of the eye and an object in front of it . This object , an arrow , is seen by means of the visual rays proceeding from it , the principal two of which are shown . The visual ray from ...
Page 255
... Visual Rays pass from objects in straight lines to the eye may be proved by the following experiment ( see fig . 306 ) : - Pierce two screens with a large pin , and place them so that the holes are in a straight line with a flame , as ...
... Visual Rays pass from objects in straight lines to the eye may be proved by the following experiment ( see fig . 306 ) : - Pierce two screens with a large pin , and place them so that the holes are in a straight line with a flame , as ...
Page 256
... visual rays , by means of which the observer sees the cross , will , in their course from it to the eye , pass through the picture plane . These visual rays will intersect the picture plane in a number of points , and if we mark the ...
... visual rays , by means of which the observer sees the cross , will , in their course from it to the eye , pass through the picture plane . These visual rays will intersect the picture plane in a number of points , and if we mark the ...
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Common terms and phrases
addendum circle Area axis beam compasses bisect blade Boiler bolt called center line Circum circumference compasses curved line cylinder desc Diam diameter dimensions direction distance dividers dotted draughtsman drawing board drawn edge end view equal erased figure fingers finished free-hand front elevation gear geometry hand Hawkins illus illustration inches India ink instruments length letters Linear Perspective machine measurements mechanical drawing object oblique Office Rules outlines paper parallel lines pencil perpendicular picture plane pitch circle pitch line polygon position practice projection proportion radius represents retina right angles rods scale screw section lines Set-Square shading shaft sheet shop drawings shown in fig shows side views sketch solid space spur gear spur wheel square Steam Engine steel straight line student surface T-square tee-square thickness of tooth three views thumb tion top view triangle vanishing points vertical lines visual rays width
Popular passages
Page 238 - Every line and letter (signatures included) must be absolutely black. This direction applies to all lines, however fine, to shading, and to lines representing cut surfaces in sectional views. All lines must be clean, sharp, and solid, and they must not be too fine or crowded. Surface shading, when used, should be open.
Page 87 - POSTULATES. I. LET it be granted that a straight line may be drawn from any one point to any other point.
Page 240 - ... at the lower lefthand corner, all within the marginal line, but in no instance should they trespass upon the drawings.
Page 18 - ONE step and then another, And the longest walk is ended ; One stitch and then another, And the largest rent is mended ; One brick upon another, And the highest wall is made ; One flake upon another, And the deepest snow is laid.
Page 238 - The scale to which a drawing is made ought to be large enough to show the mechanism without crowding...
Page 95 - From a point P in this line draw the perpendicular P B to the line AB, and on P describe the circle BD, touching the lines and cutting the center line at E. From E draw EF perpendicular to the center line, cutting AB at F, and from Fig.
Page 240 - They should, if possible, measure at least one-eighth of an inch in height, so that they may bear reduction to one twenty-fourth of an inch; and they may be much larger when there is sufficient room.
Page 87 - A Proposition, is something which is either proposed to be done, or to be demonstrated, and is either a problem or a theorem.
Page 88 - AXIOMS. 1. Things which are equal to the same thing are equal to each other. 2. When equals are added to equals the wholes are equal. 3. When equals are taken from equals the remainders are equal.
Page 53 - A sphere is a solid bounded by a curved surface, every point of which is equally distant from a point within called the center.