. Canadian machinery and metalworking (January-June 1919). at any ex-planation is hardly necessary except tosay that the spindle portion A has atongue which fits into a groove in themain body casting of jig, and in this for estimating the probable limits oferror in analyzing samples of coal andto show how this method, that of leastsquares, should be applied. It has been shown that the methodof least squares is applicable to theproblem of sampling coal; and theauthors have succeeded in deriving directexpressions for the magnitude of theerrors in the work studied, or in otherwords, the answer to
. Canadian machinery and metalworking (January-June 1919). at any ex-planation is hardly necessary except tosay that the spindle portion A has atongue which fits into a groove in themain body casting of jig, and in this for estimating the probable limits oferror in analyzing samples of coal andto show how this method, that of leastsquares, should be applied. It has been shown that the methodof least squares is applicable to theproblem of sampling coal; and theauthors have succeeded in deriving directexpressions for the magnitude of theerrors in the work studied, or in otherwords, the answer to: What is the mag-nitude of the probable error of a singledetermination, and what is the maxi-mum error to be expected, say, once in1,000 determinations? The authors have attacked the prob-lem by first carefully working out thelimits for a few coals that are selectedas typical and then comparing the re-sults so obtained with data compiledfrom numerous check determinationstaken consecutively from laboratory re-cords. / ^ I km ii--?II- LUiJ 1 I© I Ufl J. SIX-HOLE DRILL JIG. way is held in position, aided by thewedge B. Upon removing- this wedge the spindleis pulled in an outward direction whentongue leaves the groove. Work is thenrevolved 180° and placed in groove asbefore. This method ensures accuracy. Where this -operation cost 25c eachbefore the jig was used the cost afterthe jig was installed was reduced toIViC, which shows clearly the advantagesderived. — THE IN ESTIMATION OF ERRORSCOAL ANALYSIS In technical paper 171, recently is-sued by the Bureau of Mines, theauthors, J. D. Davis and J. G. Fairchild,have sought to describe a definite method The results obtained through thetheory of probability would seem to in-dicate rather clearly what degree of pre-cision may be expected with the coalanalysis when the quantities are de-fined by the actual methods used foranalysis. It would seem that the limitsallowed by the committee on coal an-alysis of the American Society for Tes
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmachinery, bookyear19
