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Texereau ch2 p36, 37

Work continues with emery 1m whose grains are comparable to those
carbo 100 or 120, but that leaves less deep fractures because of its
lower hardness.

Now we will adopt general way for the rest of the work, a
normal stroke on which it must attract the attention specially: they consist
a back and forth roughly centers (Fig 22 and 23), the total amplitude is
about 1/3 of the disk diameters (therefore it is necessary to exceed one sixth of
each side, 3 to 4 centimeters with a mirror of 20 centimeters), with a lateral departure
constantly variable limit 1/8 at the each side.



 
the shape of the strokes may well affect that of a V or W or of a loop
more complicated
as an example (G. W. Ritchey). Every five or six strokes
it turns a little the upper disk in his hands and one turns oneself as in roughing(coarse grinding). What is essential in all this is only to respect roughly 1/3 the average amplitude and to vary as most possible strokes of way that
has not always systematically move in the same way, the law of large numbers will
and the rest, unless exceptional clumsiness systematic (abnormal pressure of the hand
always at the same point of the race), the surfaces will deviate on average in that sphere
a very lower amount to the diameter of emery grains interposed


For the correct use of emery we will draw guidance data at §16 but this time, only the weight of the upper disk has added the hands of the operator normally asked (they only serve to control the movement of back and forth) will intervene. Fine grinding will be done uniformly and without change notable curvature if one is alternately dried with mirror above and one with the mirror below. Except at the beginning or the class will encourage a fair several dried immediately in the same position to better respect the curvature (position in the mirror above the concavity increases, it decreases if this is the tool that overlooks) 

After two or three dried emery of 1 m, a cursory review by reflection might suggest that the carbo fractures are eliminated; but looking at the Glass-through before a strong lamp, we see little accidents shiny, sparse on the more uniform background or emery has worked; there also has scales deaf invisible for now, but will from leaving new holes. It is therefore necessary to continue working with 1 m up that we are sisters to have eliminated all those accidents which may request dried fifteen to twenty, or even more. However emery of 1 m leaves himself of uneven fractures; it will stop when we see that abnormal accidents landmarks when the previous dried by a circle in pencil on the back of the mirror does find more in one place

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