SIR,--JI~~ I point out tliiit in your rcport of t.lw nlecting of tlic GIiisgow Section on October fi (CIII*:M. S: Is])., Oct. 13, 11. SlS), you oinittcd tlic main point. of riiy sllggcstioii. This \viis tlliit thc rcsistiincc to t,llc rcliitivc inovcniciit of t,wo Iiibriciitcd surfiiccs, untlcr t,lie conditions of the csl)eriincnts dcscril)ctl, consists of two quiintit,ics ; resistance tluc to t.lie interlocking of siirfiice rispcritics (such :is \*oiiId occiir witli dry siirfiires, tliougli to i i less cstcnt) iinci rcsistiincc tluc to iiiovciiicnt of the 1ul)riciint 1)ct.v ccn t lie irrcgiiliiritics of t.hc surfiiccs, resulting in ii puniping iirt,ion. Thc foriiir*r will be tlic Imdoiniiiiiiit fiictor iit low teuipcriiturcs and will iiirrcnse wit11 iiiiwssccl tcnipcriiture 111) to :I point. wlicrc no sonsiljly closer !ippro:icli of tlic siirfiiccs ctin occur with n fiirtlicr rcciiiction of viscosity. Tlic second qunntity will dccrcrisc ;is t,lic tciii1)cniturc rises, owing to t,lic reduced viscosity of thc lul)ricant a ~i d tliesc two opposing results of a rising trnipcrnturc iniiy girc tcniperiiturc-p curves of tllc typcs obtnincd for mineriil tinti vegctriblc oils, nccording to tlicir roliitivc iiingnitmlcs.