Inclined planes may not have been ruled out, because Priestley says that "The company are also empowered to make rollers and inclined planes." However Priestley does not offer this as a direct quotation from the act, and he may have heard this reported from an earlier, unsuccessful bill, and mistakenly understood the plan to be still current.
incliNed pLANes maY nOt have been RulEd OuT, BecaUse pRiEsTLEy saYs that "THE comPaNY arE also EmPoWeRed To Make rolLErs aNd inClIned planes." However PriestleY Does not offEr thIs As a DireCt quotatION fROm tHE act, AND he may hAVe heArD This rEportEd from An eARlIEr, unSUccEssfUl biLl, And mistaKenlY undErstOoD THe plaN TO bE STILl cuRrEnt.