rcully corrcy~ont!cci to the iictunl requir&nieiits of cnginwring prnctiw, niorc csjwci~~lly 11s in n~iiny cmcs ciiyiiiecrs were ttblc 9 0 giro w r y little infornintion ns t o thrir retliiiru-Incnts ; they srliloni knew the tenqnmturrs n t which they were working, n n t l were usiinlly only nblo to stiy thnt n ccrtnin oil siiitccl tlicir piirpnscs nntl cri-tniii other ids did not. Sir Ihorcrtoil Ki*tlwooil's virconietcr hncl Inwi tlcwrikccl lwtorc tliiit Bctioii iicnrly 30 ywirs iigi~. riiitl iikhoiigh it hricl not. hi-en i n niiy wny ~iiotlilic~d it \rtis still iiwd by ncurly evcryonc r h o trstctl oils iii this coiiiitry. That was a wonderful ti-stinioiiy to the cxcrllencc of the nppratiis, though when on(. 111okeiI n t it in tli*tail t h c w wi:m the objections tlint it did not ilircctly iiionsiirc the r i d viscosity, tlic Ireiiting nrmrig:enieiitr; were very clefwtirc, nntl SII on. JIr. Higginn IIICI sli~litly toiiehctl 1111 o w otlicr tlefcct, riii., thiit clilitw*iit cc*rtifictl instriinii:iits tlicl not n11 give thu siitiii-iriclicicticrn ; tliv vnrintioii \VRS sonict inics cnnsitlcral~lc. 'Phc tlifliciiltic*s with the instriiiiient wero ~~e r l i a l ~s tis inucli iii the ntljiiritiiiviit ns iii the tict.iiii1 riirietion o f liorc t i n i l the jvt. (hi tlic \vh-~lc it wns c ~i ivc!iiient to IIH.. S o tlniilit in t h t b pnst tlie wrtilicntioii h d lwcn crircfully clnnu ; biit 31r. Iligyins lircl shown tlrcni it. wtis nlniost oiitsitlc tlic riiiigc of the oriliilcirg prirtitc pcrwn's work t o tlcnl with siic*h thirigs. Mr. C;IIABT HIJOIW~ tinicl lic tlinii~ht IIIW 01 t tic tiiii.it vnliinblc ft!ntiircss of tlie ~I M T w s the siiggcntioii of the ritlvianbility of exprcssiiig 1111 visiwsity ri!siilts in tcriiis nf n!ir;oliitc viscosity by the 11-of the forniuln which w i i x given. Thcro WIIH no doitlit thnt ililicrciit ltctlwootl irixtriiiiicwts did .yirltL cli1ii~rc:iit ri-tiiilts with rioiiii! I ~P , though tlic iiintriiiiicnts wcro ntljiistetl with tlic striiitltircl oil. 'I'ho p p r oncc ngniii eniphnnisc.tl t lie iicccw4tg for tnking troiil~lo R l l l J i i t conipnrntirely sniiiII tlctiii~s if tic.ciiriito niitl conipnrnl~lc resiilts w r u to 1)c ol~toinctl. He thought that with rcasoiinble care no grrnt ciiticrciice might to ri*niilt froni vuriiit ioii id tciiiprriitiiru. Hu iiiinyiiiid tlint tho iiminl prncticc wiis to Iring tlio oil to tliu pnrticiilnr tenipimtiiro ntwsritiry hefore it wns pit into the cup, tliu tuiiqwrntiiru of t.hc bath lriiig iit t,lic ntniidiird teiiil~rrut iiro hforu starting. Under those cniidit.ions no yrent clitiercnccs w i w foiiiitl in trctiinl priictice. Slight' cliffcrciici-s, howuver, niiglit still h cs~icctctl Iwt\vccn tliu rcsiilts olitninccl by t H'O n i i ~i i workinK in tlilicroiit Iiibortitoric.s with tlilii~ro~t. iiixtriiniciitn. 'J'he ijiicst ioii wiiti, wcru r~l~jcit~ioris to h i 3 rained on I few tieconds vnrintioii titi ii 400 or 500 si~coiitln run ? 1'1) liiti mind it way nlisurtl to enter into cniiflict over iiiiniito tliti~!ri~iiccti iii vircoirity clittc~rriiinrtiona. Mr. COSTE writ1 thnt rnpi oi Ilii!tl ~J i ~l t l i ~ilitiiitloiictl BR H ~tiintlnrtl HiibRttinw, h i tlioiiglit.. Ibxiit ccrt.iliciitt*ti rubrrod to Rcclwootl's origiiinl viticoiiietcr IIH it atu~itliircl, and tho uneiinilition thnt rnpu nil hntl n viticonity of S h 5 weontln at, ~i i ~l i H tc~ni~wriit\iro \VIW iiow nluincloiii~tl.
instriinient wns nbout one-tenth of the corrcnjmntling tinic One of thi* viIrious siniplc tylws of rotntion instriinicnt wonltl prcihribly be suitnldc fur riitroeelliilosc rioliitions. 'I'hc visconictc*rs wcrc gcIic-rnlly ric-111 out 11y tlic mnkcrs with n cc-rtilicntc: froiii Sir Ibvcrtoii Ri*ilwoi~tl'ti nssistnnt. 9 1 1 of thcni hncl bccii ntljiistc~d by nltcriiig tJk height of the filling point to mnkc the tiniu of fow ngrce with tluit of sonic piirticiilnr oil na clcti~rniinecl nil Sir Ibvcrton R I ~\ ~I J O I ~' S stnnclnrcl instriiini-lit. It l u t l Iwcii fouiitl in viirioiis iiistriinicnts tliiit the clilicrcnco horn tho normal level might lie 11s iiiiicli ns ii qiuirtrr of nii i i i d i , nnil fiirthcr for n ccsrtniii nil two or tfirm instriinicntn might ugrw vsnctly, lurt for nn 1111 of Iiiqht~ or 11)wrr viscosity thcy \rniiltl givo -cry t l i l i c w i i t rrsiilts. Sir Ilovi~ton Ilccl~vootl lint1 cil~n~itl~~iic~tl tliv IIW of r a p 1~i1 ns :I ~tniiclriril owing to tlirclilliciilty of ol~triiriing rrninplrs of thi? snnic viscnsity. 111 the cnw of the Enghr fnstriiniciit t l i e t iinv of flo\v of tlio tiul~sttincc~ iincler iiivvst igrit ion ivns refcwctl to thnt Of wtiter, which wns 51 scconiln iii ti iiornii11 iiirdriiincwt, whenens t o olltnin thr Itc~cl\vor~l viricwity niinilwr thrrcniilts wen. coinprin.d with t l i ~ titiit-of flow IJ! r n p oil. for wliicli the constant 011 the S O . I ty]M'. Vlt~lll! 5:Is S l W l l l l ~s hlld h ! C I l I l t ~I ~~J ~l ~t ~.