PRITCHARD-NOTES ON STEAM PRODUCTION; 663 nscd tho molting point ns I L cnlibration point, but the instrumcnt wns only of uso for oxpcrimcntnl work.
It wne very difficult to ot suitable protection tubes. Possibly quartz tubes w013d do well for this. Onc dis. ndvontago of 'tho thermo-electric pyromctcr sns thnt tho physicnl laws ivcro not ncnrly so wcll k n o m ns in tlic rcsistnncc pyronictcrs, so thnt for tcmpcrntures rip to 1000" C., thc rcsistnncc pyronicter wns pfcrnblc, nnd for tcmpcrntures fro? 1000 to 1;iOo" C., thc tlieriuoelectric 'pj-romctcr. rhc therino-clectric pyromctcr conld bo put in tlic spncc of n p a , but tlic rcsistnncc pyroiiictcr'6buld not bc put into so snioll a spncc. For rough and rcndy purposcu, pyromcters, such ns tlic Uristol, wcrc much clienpcr than thc plntinnrn, nntl if they were burnt np in n few tinics,"thcrc wns not niiicli loss.
For higher tempcrnturcu, the only p~~omctcrs which were rcnlly sntisfnctory, wcro the opticnl pyroinctcrs, described bv They wcrc good np to nbout 1000' C.
_ _ thc nllthoi.
JIr. I-I. If. Vauciras snit1 his conipnny hntl used one of Dr. 13nrncs' ~yronictcrs on locoinotircs. nntl hc bclicred i t wns tho drily 'one wit~i w ~i i c ~i nnyt~iiiig like nccnrntc results conld be obtnincd. Tho iden wns to find ont \dint wns tlic tliflcrenco in tcinperntnre of tlic esit gnscs wliicli passed tlirough tlic snperlicnter tuhcs nntl those nliicli pnsscd tlirougIi tlic ordinary tnbes. I$using the ortlinnry p~-roiiictcr telcplionc, they werc nblc to gct within nlrout 20' ; ivns it not n fnct, in nicnsnring tempernturc in n glolvin piccc of atecl, tlint tho correct tcnipcrnturc could Eo obtained by tlic opticnl pyroincter wlicre nny other Irind wonlcl fail ? Tlic IVnnncr wns first used, he bclicred, in n rnil mill for trying to find the tciiil'crntnrc of thc rnil passing tlirongh the rolls, nnd i t secmed to give wry good rcsiilts. L'yronicters ~vonld nlso bc of nsc in obtnining tlic tcnipcrnturc of tho iron in tho lndlc; in order to dctcrininc the depth of chill, wns the rodintion p ~~o i n c t c r nn absolute instrument, or would it menuurc tho tenipcrnturc n t the end of tlic ciipoln 9 Dr. G. 1'. G m ~w o o ~ asked d i n t mcrc the liniits of tho spectroscope for tlic nsccrtnining of tcmpcrnturc ? Dr. I<. P. I~UTTAS nsketl why rcsistnncc pyroinctcrs would not nicnsurc very low tcniperntures ? Jlr. I. U. LESII asked if tlic pouring of the moltcn inctnl would effect tho rending of thc opticnl or rndintion pyroincters ? If tho pouring w r o not nffccted by tho scum, would tlic FGry rend instnutly, or would it rcqnirc some time ?
Jk. Nomias HOLLASD nsltcd if the mercury tlierniomctcr gnvc concordnncc ? \'hot cnnsctl tho vnrintion ; wns i t sometliing inlicrent in tlic tl~criiiometcr itself ?
Hc had found tlirit a vnrintion of 80" niight occur if the bulb wcrc not clcnncd when using tho tlierniou~ctc~ in liqiiid~.
Dr. H. T. BARSES. in reply, anid tlint most pyromctera would not keep to their rcgulnr cnlibrntion, nnd thnt I ~H ono ndvontngc in Iinving onc with a chcnp end, like tho lhistol, which could hc thro,yn nwny nftcr n short diilc, ns tho wires dctcriornted. 1110 Bristol woald not, however, stand n higher tcnipcrnturo thnn tho nielting point of iron. Up to nbout 900' C , tlic clectricnl instrument wns as relinblo ns any that can k~! obtnincd. Instriiinents wcro nioro likely to bc dcstroycd by being broken thnn by nsc. I n nnswcr to Bfr. Vniighnn, no other instrument could givo nnytliing liko so nccurnto n rending nu the Wanner. Time nftcr tiriio thc nictnl coiiltl bc brought up to oxactly tho RfllilC tenilxrnt~rc with wonderful Tho hcnt instrunients, like the FGry. lind t o