Various works have been published with reference to hardness tested on cylindrical surfaces, but the experiments concerning the Brinell and Vickers hardness are very scarce. Authors developed the method for compensating the Brinell and Vickers hardness on cylindrical specimens basing on Ingerson's assumption, and referred these results to experimental ones.
It was found that the values calculated on his assumption coincided with the experimen-tal results of the tests on the Brinell specimens, but not so well on the Vickers specimens. Therefore the next compensating factor K was found experimentally.
Put K=1/ (1+k. d'/D),
where d'= diagonal of impression in mm
D=diameter of cylinder in mm
Then the value of Kis about from 0.7 to 1.0 and will change corresponding to materials or hardness numbers.

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In the second report, the relationship between lapped quantity and lapping conditions was calculated on the assumption that the whole load was supported between specimen and abrasives. When lap makes a direct contact with specimen, the lapped quantity will be reduced. To investigate the mechanism of lapping, the load supported between lap and specimen must be measured. Experiments of measuring the electrical contact resisitance between lap and specimen showed that direct contact ocurred in lapping with very fine abrasives (e.g. Cr₂ O₂) because of embedding of abrasives into graphite included in cast iron lap, and that it did not occur in lapping with GC or WA. From this point of view, the relationship between lapped quantity and mixing ratio was discussed. It was also indicated that the lapping condition could be observed by measuring the electrical contact resistance.

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In this paper the author treated the specific grinding resistance theoretically, basing uron the assumption that the cutting action of grains is same with that of spheres when the depth of cut is small, and he found that the value of the specific scratching resistance obtained from the relation between the scratch and the indentation by a spherical indentor is given as a function of the yield-point of the material to be ground. Then the specific grinding resistance in case of abrasive-cutting-off is considered to be the specific scratching resistancc with the velocity effect, and as a result it became possible to get the tangential grinding resistance theoretically.

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Machined surface of the brass containing Pb of over 1.0% is very good in quality, because the growth of built-up edge is prevented by the particle of Pb. But the surface machined at slow cutting speed is scarcely affected by Pb, and the increase of hardness and ref.nem.ent of grain by plastic working or heat treatment give good effects on the quality of surface which is cut by the tool of small top rake angle.
Pb percentage of up to 1.0 give large improvement by decreasing work loss and time necessary for drilling more than it does on the cutting force. It means that the discharge of drilled chip grows easy by adding Pb. The brass heat-treated at 720°C has good machinability for drilling.

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