“Ifindmydrillreadilymakes2400turnsperminute，evenwiththelargedrillyousentlast；ifIbearlightly，athree-quarterferrilwouldrunabout3000，andbyanenginethatmightbedoubled。“
Thematerialstobedrilledintomedallionsalsorequiredmuchconsideration。“Iammuchobligedtoyou，“saidWatt，“fortheballs，etc。，whichansweraswellascanbeexpected。TheymakegreatprogressincuttingthecrustRidgwaysoralabaster，andalsocutmarble，butthehardersortssoonbluntthem。Atanyrate，marbledoesnotdoforthemedallions，asitsgrainpreventsitsbeingcutsmooth，anditssemi-transparencehurtstheeffect。IthinkBristollime，orshelllime，pressedinyourmanner，wouldhaveagoodeffect。Whenyouareatleisure，I
shallthankyouforafewpieces，andifsomeofthemaremadepinkorfleshcolour，theywilllookwell。Iusedtheballquiteperpendicular，anditcutwell，asmostofthecuttingissideways。Itriedafinewhirlingpoint，butitmadelittleprogress；anotherwithachiseledgedidalmostaswellastheballs，butdidnotworksopleasantly。Ifindatriangularscrapingpointthebest，andIthinkfromsometrialsitshouldbequiteasharppoint。Thewheelrunseasierthanitdid，buthasstilltoomuchfriction。Iwishedtohavehadanhour’sconsultationwithyou，buthavebeenpreventedbysundrymattersamongothersbythatplagueystove，whichisnowinyourhands。“
WattwasmostgratefultoMurdockforhisunvaryingassistance。
InJanuary，1813，whenWattwasinhisseventy-seventhyear，hewrotetoMurdock，askinghimtoacceptapresentofalathe“I