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Maps, plates, charts, etc., may be filmed at different reduction ratios. Those too large to be entirely included in one exposure are filmed beginning in the upper left hand corner, l»''yV''< '» ra-i.hu) This proof is sent to you for discu.ssion only, aiid on thu oxpross uiidci'staiulin^' that it is not to bo u.xed for any other purposo what- ever. — (Si'c (Sec. 40 (if the Cunstiiutiun.) IXCOKPOliA'fKI) 1H87. TRANSACTIONS. N. IS. — Thi- Society, as a boily, does not hold itself rcsponsihle lor llie I'nel and opinion* sial('uree, by the eminent engineer, I'ro- ie.ssor Riedler of Berlin, audits eiioinus nature completely dcnioM- strated by the valuable and ext nsivi> experiments iiaide by him and Professor Gutermuth on the .'>,tl(l(t 11.1". pl;,i,t now at work in l\iris. In illustration of the kind of evideiic ■ on the .strengtli of wliich such views are commonly hold mi this subj'ct, we may refer to iliedler's treatiscoii •• New Experiences witii the P.iwer Supply of Paris by Uom- pres.sed Air," whereon | age ;!7 it is slated that the usual efficiency of small mining plants is 10 per cent, lo I') percent. : and that even with such compressors as those used at the St. (lolliard Tunnel and by Stur- geon in Hiiniiiigliam. llireclimrlhs .d' the power i> lost before the air reaches the mains cv.n. And yet the feasibility of the economical trans iiLssion (d' power by compressed air has been criliidscd by the results of such inherently bad instillations as these. It i.s as if the efficiency of tlie st-ani engine were lo be judged by considering the economical value of uiie using Ibrty or filly insleafl of fourteen or lif- teen lbs. of water per II. P. per hour. Is it not, ..i, the oiher h;ind, al- together suri.rising thai wiih the common oeeiirrence of .suclicxireniely bad results, the sy.stein should have in any ca-e survived? Ifad it not been llir the inherent vitality and p,)wer of this m;tliod it must certainly have perished under such ill usage. The leceni adoption ol tile two great iniprovement. luave a practical workinu; effi- ciency of 100 per cent. Such a result as this is quite umittainable by any otlicr mode of power transmission ; and is due >imply to the fact that on this system alone is it possible to insert a charge of energy at the working [loint with no sacrifice to convenience and at an almost insensible cost. Without further comment or eompari>oii at present, let us pass on to investigate the theory of tliis surprising (practical) result. The sy.stem of compressor air main pielieater mul motor is diagram- atioally represented in Fig. 1 where tributing mains ; c rciirosents a branch main taken off to run a motor rossion, it exjiands along the curve 1 2, whose equation is ^> v; ^ constant and the work done is J) v" - j>„ t>„ this is spent in increasing the intrinsic onirgy of llo^ air ; the teinperti- ture rises from 7^„ to i-1 7-.7.(;L)T, ...-. (1) where j> v„ T and /)„ >■., T., are the pressures, volumes and absolute touipeiaturcs of tlie air at the ]ioiiits 1 and 2 respectively Wli.ii tlir ixliaiist opens llir temjioruture of tlic air Iklls t" that .il III.' .vs.rviiir. wl.icli is 7'., ; llir air -ivcH up hoat of tliu an.'.unt A'„ ( 7*- 7'.,), wliilf III.' pistHii .l.-r^llio work/. (r„-v,) to keop up tlir pressun; : till' Miitc of tlio -ias is tlii'ii rt'pri'Si'iilcd by point ."l. Durin- sta..'e.;l, 4, 111., piston .Iclivcrs tlic (mun.! of air at constant p.fssurc and tenipern- tuio : work <.f amount p v. beiu- done. I'art of tho work dono l.y tlie piston was, liow.-vcr, effected by tho :itmospherif prc.^urc on the other side; so tiiat the 'vl)ole work supplied through the piston rod of the eomprcssor is (■■i) ibis limy be ])Ut in the form ciT-r..). .(•3) and as K,, : see tliat thi' wiiole work done in tho adia!)atic eompr ssion and delivery of one pound of air ts equal to th.' heat .renerate.1 durini; ■= stages 1 2 and 2 3, abwtraeied during sia-e 2 :!, "nd lost in the reservoir when, as is usually the ease, thn is ot large dimensions Insortiiig tb' ,alue of 7' from expression (1) in (:{) wo obtain for tho work of a. During delivery . a further amount p v, is done ; and subtracting the work />„ v„ due to the back pressure, as iu the last ease, we obtain ;-„ v, log, ^ for tho work of isothermal compression and delivery of one pound ; or W.. :c7:,io.A. (5) Referriu-' again to Fig. -'. tlio eyele is now 1345 instead of 12345, and tho work done is seen to be much less, owing to the fact that the pressure of tlio air is kept down by abstraoting boat as fast as U is ..■eneratod, so that the stale of the working sub-tauco is rei.rosenled by Hie curvei. r = a constant. It is obvious then that, if tho air is to bo .raiwforrod to some distant iioini boforo doiio,: work in tlio motors, the most ocouomical way ol' oonipvossing it is tli.' isotbovmal mode ; •md this has long been acted on in i.iactico hs ibo use ol cooling jaekets ,„u,„l the oyliuder and ev.'U in the piston. I'or ll.o jmrposos ot a central compressiii- stati.,ii, liowever, this i> far fn.ii, an offioloiit plan ; andisonly to bo recommend ed for mining plants whore tho lu.ieetion of a spray oleold water is impossible owing I., its impurity or to great undosirability ol any alditioual mechanism. Rveu with tho very best forms ol spray iiijoetoi- now in use, the e.,ualiontotbcourv.'"ofoompie.ssion is allorid onk 'A"™ /' «' '^ to instead of /) r = a eonstanl. This is illustrated in Figs 3 and 7, the latter of which shows a oombinea high pressure and low pressuiv oard taken from an air oompressor by Messi'>. Hiedinger . work ,l„,u. by the piston dnrin. 1 . 'l. :!, ions, liave Uer, ahstraeled a^ beat. I Ins work pv„ — l>„^„^ /„„ -pv) liowever is equal to pc„-]>., '"+(jB ,)„-y>„ii„) snicc fi\ - p,.v„. y-\ 3 Thr most .succ.'>.-t'ul »:iy of prcvcntinu the accinuulalinii of heat in the compri'ssors is to do tli.> wovk in two (or more) stages. This is accomplished by allowin- Hi.' air after its pivsMiie lias i-iscii a certain amount to flow through an inturmediate •eciiver of sufficient capacity to cool it almost down to the temperature of the atinnspheie. so that when drawn into and compressed to the final amount in a second or high pressure cylinder its state is again represented hy a point on the isothermal of atmospheric temperature. A theoretical diagram, illus- trating this rase^ is .given, viz. ; I'^igure 4. Jlere the curve 1 2 is adiabatie, the cooling being snppo-od very slight, from 2 to ;5 heat i- abstiracled in an internieiliate receiver, called an intorcooler, until the te^jperalnic fails to T., ; Jiine 33 or 3 3 represents the delivery ol the air at a pressure /,, into the high pl'essnrc cylinder, in which a lurli\er adiiibalic compression np to the pressure p takes place, as shown by cuive 3 -1. I'lie pan 1 5 and ."» (i needs no further explanation being of the sainr naiure a- already explained in connection with l''ig. 2. Kiedlei ba-^ applied tl.is plan to the new installation often tlionsinid iiorse power in i'aris with vi"y great success, but as to the originator of tbi' idea iioiliing semis to be known. Professor Hlliott in bis admirable pajier on enmpound an- compressors (read befov the Uritisii Assoeialion ai Cardiff ), mentions his having seen an installation working in this way at llie Newbaltle Collieries itcar Kdinbnrgh. Iniiit as an ex|ierimeiit by Mr. .M.urison, the manager ; and i'rofessor Unwin, in bis eommnnicaticm lo the Institute of Civil Engineers, on this subject, state- that the Newark Iron Worl<,s, Conn,, constructed compound eomprosors with an inter- cooler as early aB 1881. If the efficiency of a compressor working isothermally, and which therefore wastes no energy in useless beatini: of the lir, to lie after- wnnh In.-t ill til'' timing 1m' >km>ud l)> KlO, tlun ll.c irtlciiuc} r,t' wliiil «,■ ^liaU lall t\iM' I, ii Niliipl'' ailialmtic .•miipn'»,-oi-, will be Ibuuil III br 71'.. Tlii> I- iibtuiiicil by liinliiij.' ilic liitio ol' t-lio areas VM't ami iL'iil.') ill I'i!.'. •-', wbiili icpiL'st;iil.- thu case in 4iastioii, or wo limy lind it aiialjtieally by .■valuatin.ij; -1 Wca " ' p -0 whi'lc /• = IK'p., Ill this case (■ bciu^ 7 .(6) iwr.u = 0'744 , 0-H5. •(7) ' ~:!-5'[7-'*'- i] Caw 11. Kor a siiiiiilo uiiiiii>rt!f,si)i- witli .^pray iiiji'ctioii, tlio ftHc;icii"y i.s (sou b'ij;. 3) S4i "/o or Wei _ lc„',r Vl^^^ ' Vfr" -ll- if n=i- -1. Ca.se 111. Similarly in the r!a.sc?]of twci stai;o adiabalio ooiupressiou ihu cfficicn.y obtained iVom Fig. 4 is 86.2 "Z^. Tbe i)ressure {p,) in tlio iiitiTcoolor is to bo oboaun so as to maktt the work don.; ia tbo two cylindors a iniiiiiiumi. Tliis work ir. uxprtssud by '•^-"■,^[(;;:)''* wbioli bcii)^ differentiated and equaled U> notl.ing ijives for the vulinr of ibu iccL'iver pressure /), - \/}>o P- lu tlial case (8j becouiu8 Ift'iici' /,., = 0-Si;j as above. Case IV. — Lastly, takint;- tbe ease of three 8ta!i;e compression witli s[iray injection, wliicli wouM only be lesorteJ lo tor tne largest plants : we can c.)btain au efficiently as pir Fig'. .J, of'.).')..') I • -. r /••>. s Analytically, deti'iniiiied it is '>^ = lojr, »• ,' ( '""' ^ \ r '" - ll = fsi 7^^- n - 0' 1.046 05. .(10) That tbesi' pffiidenoies arc not men' tiuurr.s deduced by analytifal sp^'cial pleadinii, and wbieb are utterly di.stant from practical r. suits, is (evinced by examination of tbe annexed cards taken from actual I'omprcssors. Tbe first. Fi,L;ure U 5 IS from RieiUer's fir>t two -Ui'j^v lonipii'^Mii, ui;iil.' nti triiil lor the Paris '•istiilliitioii by altirin^' :i futkirill iii;ii.liiuL'. It gives :i nitio ol' iictual work to isotliLTiiial work of (IS). Tlio other, Figure 7 is taken i'roui ;iii experimental twostaize compressor built by Messrs. Riedinger to the desiiins of Mr. Loreiiz. Its lit;urc is 091. Tiicsc results show how nearly tlie cyelr of a well designed com- pressor, witli correctly proportioned valves, firstciuss valve gear, and good jet injection, will iipiiroach to the theoretically predicted card. Fi-s. 8 and !), taket from lliedl-rs " Kvaitverso-uni:," show dia- ■^rnni> rroiii tlu' cililcr macliiru'-' nl' I'axiunii & ( 'd -ki^rill. '1 lie iinHii'i- rnlfi- $t tui ff /ttr. U.^ ^tr K ^n\ F,y Jt »*r mm. §07 lul.ft ^tr Hl>/ttr k Fisis. 1(1 ami 11 arc diajjraui-; t'roiii one (if tlic 2000-lior8e-i)ower (■(impres-ors, wliieh have been workiiiL; at tlio new Central Station at Qiiai de li (iaro, Paris, since the sprin;:- of 1891. LOSSK-J IN TDK MVIN KIliiM I.KUvAiiK ANIi hit b'TlON. Theneneral ujiiiiiun has hitherto heen that lotij; dislance power trans- mission by coniprt'ssed air involves of necessity sreat lossos from leak- nijoaad Hiiid IVietion in the mains. This view can, however, iio loni;er be held in the liiee nf the exp.'rimental lesiilt:^ obtained with the Paris supply pips. The tests eairied out there by CJutermuth and liiedler are the mist .Nlnui-tivo and on the largest scale ever attempted. By )iermission ol the authoiities in the Freiieli ('apital, trials for leakage and friction were conducted and rojieat-d with letiirths of pijies vavy- \\\l from two to ten miles, the diameter beinu about one foot. '{"he amount of leakage from the mains was determined by allmving them to St in 1 under pressure, and observing' the amount of fall on the •;auges a-itim ■ went on. .\s the luean result of several experiments it ajipeaiod that 2,830 cubic feet ot air at atmospheric pressure were lost by leaka-i' per mile ycx hour. This amounts to S jier cent., as the main was ime foot in diameter and the jirissure 7 atnio>jdieres abso- lute ; so that the pnssure fell lo (1, 14 aliiiospheros at the end of the lunir. If the velocity of the air be increased from l,4t), at which rate il wfiuld hn .»: moved to pass a mile of pipe in one hour, to 30 feet per second, its ;isual velocity ; then the air, instead ol hein^ one hour, wotild only remain 8 minutes in the mile of main, and the loss is reduced I" 0.4 per cent. This loss will cause a fall of pressure of about 41 pounds per sijuare inch per mile. This surprisingly good result is an evidence of the extremely eflBcient joints fitted on the Paris pipes. Thos<^ pip 's are of cast iron with plain 7 iiiilv, iiiiil iirr jiiinlKl liy iiii'iin> nt' iIum' r:\M iriMi riiii;:' aivl I'niir IkiUi* act in;.' on two rliiMtir (mckinn riii'.'H, Hctti'V loiiltx ivi'ii tli:iu ilic.T run ii rtiiliilv l"' Mli(;iiri(il willi ii> w lipain> r(|iinll) will lnitl, fnrllu' ri'Millv.'ivrti liv ({iidlrr include! i^cm ral luikniiHU li'w.s Mirli i)h (ln' |int'iiniiiiir i Inck >_v.»tc ni ^iipiily, ainl rhnt tn sDHif cniiill nioliirs wliiih rniiM nut, lie '.((ijipnl. rri!Vli>ii«ly t(i till' liiiL'i' si-iilo anil ran liil wmk nl' nil llir Milliji'ct of lu,-« 111' picM^ill-i' liy t'fii'- ti(in of air Howin); in lon^ pipes w.it tltnsr nl Aiwm (v. I'.F t'.!'',. \'iil, (jH) 111' IJiivillr/. im pi|ii> 11]) 111 "t iiirlii- ilianii'UT, and Dl'Slnokalpt'i' mi till' ti and ~\ inch pipi - siipplyiiiu llniiiill- in tlu' St. (iiiliaid Tnnni'l, Taking thcHC older v<'>iilts and tlin^u nlitaincd ftt I'ariw tnijollii'r it appcar-i that they aurcc l'a'il\ wtll, pinvidcd iho on effirii nt of (Viotinn lir >iipposed tn diminish as tln' .-i/r "t' tlio pip,- im-rpB^i'-. llnwin ha* dison«i-ed in timr papi i" (\nls i:?, (•:<, 03, and Kl.i) in thu I'rnn'oding- of the Institution nt' (Jivil Knuinocrs the i(iiesiion ol the loss duo tn t'rit'tion of air flowing in long pipes. For the ooefficiont of friction he ;^avi', usdnu D'Arey's foniinla, in 1880, :. 0.002- ( 1,-J^) rvido also " Encyc. Britt." flX) " Hydromcehafiics " ] ; and for the pressure j;. nt the supply en-lnfa lenj^th of milin 7y. of diainetrr f/. when the initial velocity is »|Tect per seiond . ln' nhtained ., = ,J \\- iJvA] (11, If we choose to insert the value oT : as depenilin^' on the diiimotur. then we put for C in expression (11) Hie value - ) 00: H where Unwin's I'nrniiila has been slightly altered to suit the experiiuenta results obtained by Hiedkr and Gutcruiuth ; which •rave fur pipes 1 foot in diameter : =0.003. I'utting then inequation HI) this value for : and 5280 for A we obtain /'- ■V [' - (^« {50(/ "'' C.lKiOf/' .)]■ .(12) 4 ''' " 1 " If it be allowed thai one sicani hnrse power will compre-s 3(iO enbic feet of air at atmospheric pressure up to 7 atmospheres abpolnte (the uew Paris compressors do from 407 to 440) then the volume passiuff any point in the mains will be J-- cubic feet per second for eacli horse power. We must therefore have // 10 H Inserting this in (1 -) we have rr ^ :ii»25 X i^:ir)0(/' which is in a emiveiiieiit Inrni fur ealculatiii|; the si/.es of mains ; where the diameter must be hxed by the relative rate at which first cost in. creases and runiiini^ expenses diminish as the pipe ^ets larsrer. 8 .(IH) V[l .''' )1..,14 3(»25>:«lll)0«f 'J t' \l ' M T^ ^, Jn finuro, curvos liavo been ilrawn rn-onliiialiu^ tin: >i/.os ol iii;iiii ri'ijuirod with various initial volni^itifis tor 1,0(M», 2,01*0. 5.00(1, in, 4 10,000 horse pnwi'v. The luwtn- cui vos siiow tho loss ol ]irosinv prr nuW in prrceutaui' of thoori.ij;inal pivssun' for all the cases. Taking, - . ;/■, 'h'' 10.000 H. V (;nrvo> wo tincl thai with an initial vclocitv of 45 t'cct per foc. and a consefjuent diameter ot'2 li'oti'or the main, tho poreontago lossot initia prosRnre is I!."! per ecnf. per mile. The air Imvio;; now arrived at the motor.- may lie allowed to exjiaud adiabatioally, '.«■.. without addition of hnat. or it may he warmed dnrins; expansion bj" a >pray injiTtion ; or ajiain it may he worked in two stages and warmed in an intermediate reeeivm' of sufficient capacity. Thf best mode of usinj; the air. however, is to p^ss it through a heating stove or preheater, and benin expan.-ion in the motor.- with air at as high a temperature as is eonveniont. the exp;ni>ion afterward taking place aloni; the adiabatie curve. If the motor he large enough to warrant the necessary primary outhiy. it .should indeed bo heated twice, being delivered by the high jiressure cylinder at a pressure of two or three atmospheres, again pa.ssed through a heater and expanded ill a largo cylinder until its pressure falls to that of the atniosphcrc. Consider then, Case I, Figure 12. a simple motor with no preheaterj no injected .spray, I.e., adiabatie expansion. 9 5 k :) *» V ^ s • i <^ (t ■V. c k Vi n :s v.-:t The air enters tlu' motor t'rom thf iiiiiins at pressure, volume, unci Uimperature, denotei' by /), (', T",,. It does work of atiutuiit , Vi "< - P., ", = 7^(p, ".-;>„ «,)".(15) = -^l tbat the air expanded isotliermally, heat bi iug added from the stor; iu tlie atmosphere, '■ would do the work. w,„. = c r„ 1*.', >1 .(19) The efheioncy of the simple adiab:ilic lUJtor is therefore _ir J^iV'Kp) ' J .(20) log, -T-t Pu 111 Ibis case /), aiid^), are o.i') and I respoetively, .so tbat 1.6718 '" This is illustr;;ted by diai^ram No. 12, wherj the white card is thnt expi''''od from the nioior; the shaded areas show the los-es iu compressor, mains, and motor respectively. If there were no \11 of pr.wsure in tlie main,':., exijrjssion (18) would be changed to "•„=.■»■„[.(&)-] .(21) sn tbiit the air ^ains iu v ilume ly its i'all in prosure, the effect due to pijo frictiiiu beiiiij; U> make tiic rate of expansion in the motor less. The ratio of the works done in two perfect motors workiiifi' one witli and the other without loss by pipe friction is l«S„ ^'' 111., ^ 'p., Iffw -- 7 mid J). = (J.5 Ibis ratio is iri'" = 0.9U4. 111 .(22) The total thei'modynaniie efficiency of the syi*tem or the ratio of the indicated work of tiie motor to that done on the Hiuii>lB adiabatic compressor (Case I) is then 0.77 X 0.9t;4 X 0.744 - .554. Allowing 0.85 for the mechanical efficiency of this prime mover driving tiie compressor, and 0.9 for that of tiie motor, we have 0.85 X .554 X .9 = .423 for tlie total efficiency of the system. Or 42 per cent, of the work indicated in the steam engine is delivered on tlio brake at the motor. Case II. With spray injection ; but otherwise as in last case the work would bo were n may be from 1.25 to 1.4. •(23) Case III. In a compound motor the air is exhausted out of the first cylinder into a large receiver at atmospheric temperature, mid is thus, or by mi.Klng witii a ji't of spray, raised in temperature (nearly) to that at which it entered from the mains ; which, if no preheater be used, will also be that of the atmosphere. In this case the work done in the high pressure cylinder is Vi H (,..-;yo-7;^>L^[i-(ii)rj That done in the low pressure "ylindor is The Work done by bntii is >-i ' >'-•. P-(;:)^^"-(;;.)n '^^) If // be taken khuiI to v)'. /'„ which uivcs maximum work in the motor iind equal jjower developed in eiicli cylinder ; tiicu ,r„.,„.,:,^[i_(£=)'f-'] ,25, If this two stage motor be sujiposed supplied fivmi a three sta<'o compressor working with spray injection (Case IV of compressors) tho the total therniDdynamie ottieieney and (he total working otlieioney - .7(!5 x 79t! = 0.01. Case IV. Let une pound mass of air arriving from the mains in 11 till' .■-tall />, / 7' lir ln'iilcd al loiislaiit |ii'eivr !""> a Irriip niKiiL' '/',, ■11 that its vulumo iiioirasos In T.. If the expansion In' ailiiliatic thr work ilniH' in tlic liisili ))i-('s>uri •ylimler is IK <■. + /I v^, _ p' v' - ))' >■' ^ }>' '■;- ; /J'.v, -])• r'\ -'■-,['-(<)'''] 1 Let tliL' air then oxliaiist into the low pvi'ssiiiv cylindei' jiiiss'iii; ihrougli a second small lieating stove ou its way. and thereby lii'inij raised in temperature aL'iiin to 7',.. H The work dnni' in the low pressui'e cylinder with adiiihutie expan- sion down to the atmosphere will he > - 1 (/'•'" - /'"'v) ~ 1 and till' t'llid work when />' = '//>,/'„ is "-'-'■^';-i T'-c;;)'^ ^-") So that the work ii^ pounds ol coal pci' hdrsc power per hour. It will be remembered thiit it was found advantageous in the com- pressor to keep down the tempuialiire by ab.straotini:; heat durin"- compression, which is delivered to niitnr;d reservoirs such tis water or air at atmospheric temparature. Similarly we see that in the motor the most economical umde of doing work is to keep up to the isotlier- mal curve as much as po.asible by adding heat during expansion from these same natural sources, water and the atmosphere, either by injecting a spray or by using an interwarmer at atmospheric tem- perature. ^•, Prtssure tn mains' Staff, 13 4 IIP MOTOR Fitj ta It li;is long been ilic custom in I'aris to use a small stove through which the coinpre.-semiited in;o air under pressure is ex- traordinarily efficient. It is almost wholly convened into mechanica effect, 'i'his Would lead «.>> lo consider the highly interesting question of the theory of the prehciiter. The author prefers, however, to withiiold this for the present, pending tln' eompletion of some experiments now being made on the subject ;it MeliiU College, by which he liopcs to be enabled to 611 in the nccessiry constants in the expressions obtained for the heat transl'crred into the fluid under given eoiditions of heating surface, tem" pjrature difference, velocity, and dryness of the air. Suffice it for the |)resent to give the following piactically realized data for a motor of one brake horse power: — the air can be heated from GC-' up to 400^ F.,wiih a stove whose external dimensions arc 8" diameter and 1 2" high at an expenditure of 0.4 1 pounds of coke screenings ])er hour ; while for a motor of 40 horse power the preheator need only be IG" diameter and 2^" high, and will require only 0. "22 pounds of fuel per horse power per hour. The possibility of the subsequent addition of energy at such an insig- nificant cost is a special characteristic of this system of energy trans- mission. Such a supplementing charge can indeed only be administered when compressed air is the working fluid : and by this means not only can the heat uselessly produced at the generating station and lost in the r.iains be made gnol ; but, as has just been shown, more heat may be added than was originally lost, and the motor may at a very >inali expense, ami without any additional tronblj or inconvenience, give nut more power til I! was si>entOD the ednipres-or. In rerercnce ti this point it may be stated lint the air ni ilur- and pre- heaters in J'ai'i> iire allondeil to, -]ieiiinps mme correctly >tati'd are left nnal'ended, — by waiters and donie.-iie servanis wiui have all manner of other employ menls. A 1] they lia\e lo do is lo Inni mi llie air-cock, re- fill the lubrie.itors, and ]nU on n >liii\eliiil df f.iel one m twice a day. As J'rot. liit (Her has reinarKnl. llir uir inciter M]ipe;ns to be even a more hmg -ntf. rinu niarliinc lliaii tlie steam ciejine, wliieli i> so de-ei'v- edly celebrated ill this ies]ieii. Willi regard to llie amount of lire- heating to be le-ortid to, this ile]iends on the nize of uioior and the desired tempeialnre oi exhaust. If tin' motor is a Itiige and powerii.l one it may be advisable to n^e two luaters, Imih a preheater and an interlieater. l''or motors r,f 1(1 horse ]iowei and under, however, one will usiinlly be sufficient. Jl'the air entH.Ms witliout jirehcating it will be exhausted at temperatures lioni 10^' to :i5^'F., in wliicli state it may be used fie vA\\ storage or other similar purposes. This is largely the case in .'alis, where in iiiiiny leslaui.ints and eilVs, ;iir motors drive tlie dynamo> (nr iigliliiig, and the eseajiingeold air is .il'teiwards led into reliigeralii- for iihvioii> pui|iO>e^. Cnnfectioiieis again u-^e the motor during tlie day to drive the mixing and other inaehines, light their sliii]).s 11 tiie evening, and use the e.xhaiist for making ice. 'I'lie exhausting ol clean cold air into a workshop is a great advantage in a hot climate, if. on the other liand, reeimrse is had to a considerable amount of preiieatiiig, the air will be exhausted at or oven above atraosjdiei ic tempi ratuie ; and with a large motor, enough warm fresh >ir may be obiained to ^rve in winl r for heating and ventilation. 14 In concludin,!; this part of the paper it will bo well to recapitulate iu brief tlie several efficieiicie;; of the different jiarts and the ciind)ined effi- ciency of the whole system for one or two of the cases must likely to occur. The mechanical efficieney of the comprcssin;; machine may be safely taken to be (I.8U, the I'liris inttalhitioii coinpicssors ;,'ave this result; and with the new 2000 horse compn ors Riedier has obtained 0.0. A turbine will ,ij;ive from 0.75 to 0,8 for the same ratio. The thermo'lynamic efficiency of the coiu[)rijssors is for a single stafe compressor with spray injection 0.85, and for a two 8ta<'e compressor 0.92. The loss in the mains due to Icaka'j-e and fall ofpresisure for a 5 mile trau-niissiun may lie put at JJ.S per cent., so that the efficiency of the mains is 902. The therniodynamie I'fficicMcy of a simple adiabulie motor without prcheater is 0.77 ; of a two staijc adiahatie mutor 0,9; of a simpler prohoateu motor D.S to 0.9 ; and of a two sta^'c prelieated motor 1 1 to The total efficiency or ratios of the hriike horse of the motor to the horse power used in the comprcs-ors for the two Ciises which we liavo to consider in estimating the tiuancial possibilities of a pneumatic pov supjily arc therefore as follows ; — Case I. Turbines drivini,' best compres.sors, power transmitted througli 5 miles of main, larL:v-t nir motor for faetory, with two sta'^^e he:iter, Kasily possible : 0.92 x 0.9(! x 1.25 = 1.1 Actually doni': 0.90 .x; 0.96 x l.IG ^ 1.(1 ' Case II. Turbines driving best oomi)re,-s(irs, power transmitted and distributed by 7* miles of main, medium shu'i] simple air motor with piehrater, 0.92 X 0.94 X 0.87 = 0.75. Case III. Triple expansion steam engines driving best compressors at central station in or near city, power distiibutod in 5 miles of main and consumed in an average simple prelieated motor, 92 X 0.9() s 0.87 = (j.7t). The meehaiiieal effieieney of the turbine or steam engine is here left out, as it will be allowed for in the estimated cost of a horse power delivered to the compressor. In entering upon the cunsideiation of the commercial fca.sibility of a transmission and distribution scheme by compressed air, let us direct our attention to a concrete case, and postulate the conditions which ob- tain in the Incaiity in fjucstion as regnrds cost of coal, nature and amount of available water and other power, Ileferring, for example, to Montreal, let us take fcr granted that an abundiint supply of water with a fall ,A\ say, 20 feet can be obtained 5 miles from the city ; and that all difficulties in connection with the utilisat ion of this power, such as frazil can bo, as the author believes they can be, successfully oveicomo, 'J'his being the case, let us in the first place consider whether power can be supplied cm a large seale to a mil owner at anything like the same price as he can make it for himself by burning coal in steam boilers and using the steam in a first class steam engine. First then let us ascertain at wln>t price per hor^'e power per aimum. a pneumatic power .-upply company owning its water supjily can af- ford to deliver to a consumer 5 miles away dunpressed air at a pressure of, say, 95 lbs. on tin; gauges. Trom statistics and data given by Hwain, .M ir .lu;.^ and JMaiii, it ap- pears that the cost of one 11. P. on the wheel i.i.', that is lor dam head and tail raises, turbines and sliai't, penstocks, gates and wheel-pit for a 2,0(10 II. 1'. phmt, varies from 617.00 with a fifty Ibot head, lOf) foot distance from supply to discharge, to JJ153.00 with a ton foot head and a distance of 000 feet. (See Fig.) 15 f 200. f ISO CVR VES coordinating cast of whttl- itk conditi III the CISC of the works now approaching completion at Austin, Texas, the figure, as iiindly supplied me hy Mi'. Lea, of McGrili College, is $14.00 for ail average head olTiT feet and a distance froui eanal to river of 600 feet. In the present ease it has lioeii assumed that the cost of one wheel H.P. is $90.00 ; which will allow, with a head of 20 feet, a di.stauco from supply to disciiarge of about 700 feet, or, witli a head of only 10 feet, a distance from river to eanal of 100 feet. It will jnobahly be admitted that this is a somewhat liiiih estimat for this lotatiou, where the average head may be expected to be from 20 to .'iO teet, and the pr..ssibility ol dispensing with a dam will allow for almo.st any reasonable length of .-upply and diseharge eanaN. The ti.xed expense.s on this eajiitul sum are here taken at interest 't per cent,, ep.iirs 1 per cent., dejireeiation, etc., 2 jier eent., or a total of S pir cent., which on .S'.IO.iKI iiiiiount- to .^7.2(1. The running expanses, including atter.diinee, uil and waste, are tMken at .S0.7"i \aw II. P., uiakin- a Ida' annual expense per H.l'., .--nplilied at the turbine shat't of ST.il'>. The eomprcs^ol•s will eo>-l considerably le.-s than a steam engine of eiiu;d power ; i'or idthougli they cannot he said to be now in the market iu this couniry (tlie highest type of modern Hrsi class compressor being here iu ijuestiou), yet ihi- will bo more than loinpensated for by the luck of air and eirculatiuL mips, and the fact of there being no erunk shaft to charge against the compre-sor, ibis having been already reck- oned along with the cost ul'the turbines. The cost price of compressors may lin'i-efore br taken al 810.011 per gross HP., and if we take the fixed expen.ses at ; -interest 5 per cent. ; depreciation 4 per cent., re- pairs 2 per cent., together 11 per .:enl., and tht; running expenses at 75 cts. pir 111'., ih.- total cosi per II. P. per annum of compressors is «1.85. The twelve inch cast iron main~ w ith special flexible joints, as u.sed in Paris, may be expected to cost S30.00 per ton ; which is at the rate o' $1 00 ;ier runiiiie.; *iiot. Adding 25 ots, per foot for trenching and hiyini;, we obtain a total of ;j3;i,100. or $lti.r)5 per H. P., for 5 miles of 12 inch main. Taking interest 5 per ei'nt., depreciation 8 per oent.i repairs \ percent.; together SJ per cent., the co.xt per II. P. per annum itmountfi to $1.40, 16 'J'hc tdiul iii>i |Hi' aiiimia to llu; I'owi'i' Supply Cuiiipany of one coiiiprc'csor liorsc pnwor is Wiitcr I'ciwer $7.;>5 (Jouipressorn 1 .'^;> Mains 1.40 Ul;l Kllillnl > produce one H.P. But in order to effect this it is only nce.Msary for the mill owner to tit as part of his motor plant, one or two heaters to supply the energy lost in tr.in.-mi>,MoM. The cost of the motor, including these heaters, may be e.xpeeted to be less than that of a steam engine of the same power. But, takiii- the cost at gl2..")0 per H.P., and reckoning on this, fixed ex.ponses at the rate of 11 per eeiii., vi/,., .5 per cent, interest, 4 per cent, depreciation, li per cent, repair. ; taking also $5.00 as the cost of Uie motor hous.-, with 10 p-ir cent. a> fixed charges, the total cost to the C(msumer of his own power plant is $1.90 pat H.P. per annum. To this must be added the runnin;: expenses as follows : — One man :it «2..>0 91M Oil waste and supplies 0.80 Goal for the two he;ilers at together 0.3 lbs. per H.P. hr. at •S4.((l) per h)n_u ton 1.65 Total «4.01 The ail discharged by the motors will be of sutficient amount and at such a temperature as to heat some portion of the mill; but for security wc shall add a plant for heating alone of one-fifth the size of the original >U'aui plant replaced by the air motor. This plant will cost about §15.00 per H.i\, so that thi> capitiil outlay will be $3.00 per H.P. "f power. Taking the fixed expenses at 12J \m- cent, on *3.tl0. that is $0.38; the running expenses (vi/,. : co.d at $2.00; attendance, (one man at !? 1.40 for 150 days say $0.42) at $2.42; the t«tal cost of this heating plant per h.orse power of power plant will be $2.80. Adding toijcther all the items of the mill owners annual expenditure viz. : Ccst of air supply .$17.(»3 Air Motors 4.01 Extra heating 2.80 $23. S 4 Wc obtain a total of ?f23.S4 as the annual cost to the mill owner ot his air supply, air motors, and steam heating plant. With this we have now to compare the eo.-,t to him ol' steam engine and boilers of the same power. Assuming with .Mr. .Main ( f lans. \m. Snc. Mcc. Eng., Vol. XI) that the consumption of eoal pjr I 11. P. [>cv hour of a compound engine is 1.75 lbs. :md of a high pressure engine 3.00 lbs , and allowing that 25 per ct^it. ol' the steam exiiausted Irom the high pressure cylinder is taken from the receiver for heating purposes, we obtain a consump- tion for this comliine• 308 -h _) Sll 35. For boiler attendance we must allow two men at 2240 ' $1,50 and for the engine one man at $2.50 for every 500 Horse Power or ('^'*"^ ^'^"^ = ) $-'.40 per H.P. per annum, With $0.80 N ,')00 ^ 17 for nil iilnl wislc aiiJ no uUnwaiir.' I'drco-t of I'l'Cil or lix ">ii cimilciMiii^,' w;it.'r, wliicli iiiv sii|i(tiis.'.l t*i Ih' ■.ii|i|.!iiMl fri'O by cnu'iiu; ririMiliiliiin |mui|i, ill.' luiiiiiii'^ oxp.'iisis iiiiioiiiil ti> 814.01 |M;r II.P. ]pci' iiiinuu.. The ti\iil cxp MMS iimst hr rcvkmiod nil id cost of boilers, cnuinos :inil house-, lidilurn of tliu Hiibmck Wiieox 'ypi' cost about S^'iO.OO pev HI*, and s5.0(t for >vtun'j,. tonelher »2.').0(). With intorrat iit 5 pcf iviit. , rlepn- (•iiilimi 5 poi- ci'iil., taxes iind insurance 2 percent., repairs 2 per cent., losiellier 14 piT eent.,this works imt to §3.5(t fixed expanses on boilers. 'I'll,, boiler al houses ami chiuiiiey cost about ?0.()l> a horse power, uhieh eomes to $il.(i(l per U.l'. per annum, if interest, flepreeiation ami repairs be taken at toi;ether 1(1 per cent. Tiie first cost ol' a st^iaui en;.;iiie in the neifrbbourhood of 500 hors,. power is ?10.00. with 2.'> )>er c -iit. For setting, $12.60. Takiiif; the ehavL'Cs at 11 per eeni.. viz. : Interest 5 per cent., depreciation 4 per eenl.. repairs •.'I'M- pent,. th-Hxodeostorthe enijino will amount to $1.40, while the eiitiine b. use costiiijr S5.(l(l, at 10 per cent., increases this by .SO. 50. The total exp 'iise iiieiiired by the mill owner for the production of jiower by steam is therefore : — Fi.rril '■.rpi'ii.iis Boilers 83 50 Boiler bouse and Chimney.. fiO Engines 1 ^0 HnL'ino house 50 JtunnSng expenses ^'"al '^ -^^ Oil and waste 80 Attendance 2 46 $20 61 per horse power per annum. The cost of a borso power supplied by means of water and air was found to be $23.84, bence we see that so long as coal remains so abun- dant and cheap, and can be so cheaply transported by land and sea, other natural sources of energy will continue to be of an inferior value. The great transmitters of encr.'y arc indeed our railways and steam- ships, which transport at a rate infinitely cheaper than by any other mean's the enormous stores of mcclmnical energy accumulated in our coal fields; and that in any re(|uired amounts and to any distances, unhampered by the losses of power which inevitably iiccomplisb every transformation. ^ The only chance for a eommcreially successful utilisation of water power in a neighbourhood well situated for coal supply is a case where the capital outlay for water plant can be reduced considerably below $!i0.00. As. for instancr'. by the accident of great bead ; snob natural fitness that the suiiply and dischavge canals may be short, or that a dam is not nwcssMiy. Then and then only can power be supplied to a distant mill by means of compressed air at a price which competes with the cost of" production by ste nn at the mill or factory itself. Tf. for example, we take the eapilal outlay at «2().0O (a point .shown on the diagram near t he lower limit , instead of $90.00 for power dt livered by the turbine shaft, then the annual eost to tin' mill owner of bis air supply, air motors, and steam heating pliuit on the same scale as before is"reducedto815.3l. or about two thirds of its former estimated cost, one-fourth less than the ealeulated cost of steam. It remains for experts on water utili-ation in this district to examine whether a source of water power supply cannot be found, such that the initial outlay per hor.se power delivered to the compressors need not be more than i«60,00 ; i„ which case, power can certainly be supplied on the pneumatic system at a cost less than that of sieara oven to a large factory wovkin- full time. It will of enursc b,' observed that in these two estimates ot trans- mitted power, it ba sbcn tacitly assumed that the horse power indicated by the motors was the sann^ as that given to the compressors. .Not merely can this be certainly secured eren oh th' motor /)r«/.-c with suih an insinnifieant exiienditure of coal as that mentioned above ; but, as "has been actually etfeeted with |.laut, far from being near the limit of tha t v.hich IS technically ix.ssilde, an actual gain of work is possible, a working efficiency ol 116 per Si'iii.tMlj to ^:i0.45, or tlio same as tliat of steam. Let us now turn to the ease of an employer usiii;j: a small amount of powor, anil wt^ shall tinil, as is well known, that he must fall an easy prey to our central powor supply company, even if he does not use his power intermittently, as is almost always the case. We have seen that the air couipresseil at a water power station can he ilelivered to a city live miles away h)r 82o.S4, when the cost of water plant is 89(1,0(1 per horse jioiver. 11' we increase the price to 8-5,f)(> we shall have allowed lor uhout .") miles of U inch mains in the city ; and the supjily of consuuii rs at this rate allows the Power Company 10 per cent, on their capital outlay. We shall assume that a ten hor.se air motor ;,;ives out on its hrake for a given quantity of air only 75 per cent, of the power used in com|ire.ssing that air. ExpiM- inients made on the smallest motors id' less than one horse power, com- monly used in I'ai'is j^ave this total efficiency at close on 5(J per cent,, while larger machines, iis a general rule, simply old steam engines with verysniiillmeehanic.il ellicicncy, gave S(( per cent, with hut HO" F. preheating of Ihe air and a coal coiisun)|ition of J^ pound per hor.se power per hour. Then our .-mall consumer must pay S^.j.OO .\ J == $;i3,')l{ for the air reipiired to deliver him mii: hnikf linrnc ptiwn- : not uiie indicated which he usually jiays for. If his motor and prehcater cost him Sli'JOd per hoise power, the fixed charge at 10 per cent, will be %?>.'.\() ; and if he uses 0.2 pounds of coal, his running expenses will he #1.10 per hor.se power per aimum when lu( works .'J, 080 hours a year. The totil cost to this consumer of one brake horse power thus amounts to : — Air $33 33 Fixed charges 3 30 Kunniiig expenses 1 10 $37 73 837.75. This assume-; that he works at full power for 10 hours a day during 308 days. If ho works only at i powor, this price will bo reduced alnio,-l in proportion ti the smaller power employed, as the air motors cut off automatically : and if he work intermittently, it will be reduced in the same manner, a-; he is only charged for the air which actually ]ias,-es thiou;.;li his meter. For cxam[)le, if his 10 brake horse power motor works 10 hours a day, his pu'ver bill will be $377 per annum. If he runs oniy live hours a day, the amount sinks to ^210; and smaller i|uanti(ies in the same jiidi)ortioM in.'t:;d out with the pre- cision of an ordinary gas nn t'jr. This cstimati^ is ba-^ed on an assu" med necessary expenditure of 890.00 for wates ;ind wheel plant. The author believes this to be a very high price for Maiitreiil. The cost of a horse power varies in .\Iontrcal from $(iO to S120, rented to or supplied by c.nisumers using fiom 3 to 2') hoisj power ; so that on the lowest estiniatJ thc^e would save fro n 622 to $39 according to amount used, p :.■ horso power pT aiiirnu, hy a syst;m o compress(>d air di>liilmtii>n , Ijut us now io'iuire wliat ean b' do;i ■ by gon Titinj p nver in a (-'entral Station n Mr Uie c'.ly, hy m ;iii ; of tir,it class Irlpl ■ exp.in sion steam eni;ines and lirst clas-; ei)in|)ress us ; and distributing the same to customers ill a main of a length of two miles for each 2,000 horse power. Without troubling the .Society with details, the schedule of aimual charges will run somewliar this : — Fi.ri'd f.rpiHseit, toilers $3 50 IJoiler and Engine hou.ses and chimney 1 20 Triple Jvxp.insion steam engines 2 2.'! ('ompies.--ois 1 10 JLiins (12" dia.) 50 liinniiiiij '.K^jfHSPS, Coal S 2S Oil waste etc 1 00 Atteudance 2 KJ *20.33 The total cost to the Central Station Coy. of ouo compressor liorso power is thus $20.. '!3 which includes 5 per cent, interest on their ex peiided capital of $71.37 pjr horse nower. This outlay is made up a.s f diows : 19 t-« High-I'resssiucboilfrs ;ui'l .HCltiiiu iJ'Ja.Olt llouHos and cliiiiiMi'y 11. OO Triple i'ii;:iiiisi 1111(1 scitin;: 1>^.75 ConipicsMJis 1 11.00 Mains 'i«- Total *'l-^7 Allowinj; .') ]i, nr s'.iSu, we liavc a total of C23.'.M) ; wlich is iho piii'o at wliidi the Central Statimi CdUiimny can supply air lot nnuliorso power ami miiiiit ai tlio >i\un' tiiuo Id per cent. intLTi'.st on their uapilal outlay. Tiie e per cent, to Ti") per cent. ! il oir^ht to be uieutiuued tliat the lower limit ol' savinj;jn>t uieiilioiud, as-uniia that tli(iiinHumrr>i' steam engines, which, without alteration, will serve e(juaily as air uiutoi!^^ have a present value of ^liH.OO per horse [lOwer. IJegarding the .|Uesliou of heating in winter, there seems every possibility, in view nf tiie sueeesslnl system of st'am distribution in New York, of being :ible to supply heal by laying ni;nn.j to tiie city from the Central i'ower .Station, and leadiug llie exiiau at an enormims saving of liiel and expense to all concericej. This would also lie a luo-t lUsirable scheme from the point uf view of the elimination oi' smoke from our large eitie.-. The great benefit to small produe< rs Ijy sueh .-i great reduction in cost of power i.s obvious and iieul mU at present euiployour further ultcntion. Jteliirenee ouglit liere l» be made to many advantage-^ apart I'mm the question of eost wliieli attend the adoption (if the piieumatie system of power supply. In tlie lirst rank we may plaee the elimiualiou of!*.') (ler eent. nf the smoke vfhich now remhrs nianulacturiiig conlres .so obno.xioiis from an icsthetic point of view, and of the dangers and responsibiUty attending the use ol' steam boilers by unskilled persons, these bein.; done away with or removed from the more crowded parts of tlic eiiy. Tiie po-si- bilityof running air motors in the eenire of tlie city, where a, supply of water for condensing or even feed is e.xtfeuiely cxiien-ive, is au obvious advantage. The extreme ban lincss oi the working medium and its suitaliility for use by teelinically unskilled attendants lias already lieeii .adverted to. In this respect the air motor biars away the palm from the electric motor, the gas engine, and even the imicli enduring st am engine ; all o' which reipiire a certain modicum of knowkdgc or experience. The repairs al>o of such a niaehiiie reiiuiro only ;i kuuwledge of per- fectly well understood mechanieai details. Tlie use of the exhau-t for either lefrig ratio:!, veiililation, or even heating reuders tl>c rejected air a beiielicial liy-produet, instoiid of a nuisance, as the exhaust from a steam engine certainly is iu summer. The suitability of enmpressed air liir tiie working of lifts oii-ht not to escape mention ; a cheapening ol' the fir,-t cust of al least HI per cent, and of running expcn.MNS at the rale of 7.') p,r eent. over other system.-? can be easily attained. Tram cars worked by coiiipressed ah are now in u-e in Nantes^ Brussels, Chester, and other plaee> ; they have there proved both serviceable and ecoiiouiieal in spile oi the faet that the power they use is generated in small compressing stations. A r. .servoir etipaeity with air at a jierfectly s;ifo pre-snre can be obtained with an ordinary sized car to do a return jouriu'y of .') miles without any intermediate charging station ; and the C(iiise()Uent removal of a dangerous overliead wire, such as is used on tile electric trolley system, is not to be dj-pised in a ixiptilous city such as this. The difficulty (d snow C(Mild lie over- come by iiaviug a car devoted to el'-ariiig tin.' tracks alone; but this will be preferably effected i.y having a ligiil oVerh-.-a-l laihoad, as t!ie ruts in the streets caused by k'X'ping a ekan trann-oad in winter are extremely unpleasant, not to say dang, rmis, to oeeiijiauts of vehicles. The convenience with wliieli eompre-sed air as a working agent could repluce steam in a city already suiiplicd with power by a number liO ofsiii(illst.uiii cnttiiics iH sufficiontly iM.licatiMl wh..n it in Mtivb.-.! that all tiiat is m!ce*il.r :inii .•onncol. In the air main ill tl;<" sii.'ft witli thr iiii.i]MHiti()iMil ,i p.Mliioinsi valve ami an air luvU-v. Tlir stuiuii tn.il.r tuny lli.ii hv sciM and tli.i cii-'in tendur may (U'vol.' mtaily liis wholo tiino to otlior duii«s. Tliu Imw primall indu-trirs ,till mon^ marked. Wo have concluded Irom tlu' ualeiiiations above elaborated, and which are ba>ed upon results aln.;idy obtained wilb th.^ Popp syst^im in Paris, easily improvable, thai a -leatoconnmy io ilui e.wl of power to small employers can l.e effeuted by the adoption of a •scheme for the oentraiised production of nieeb.mie d en r-y aul il- distrib;ition by th.' use of com- pressed air. The (luestion now naturally arises : Is tliis inicourafiemunl of small employers a wi-e thin- to :dm nt fr.im the poi-a of vie\v of the whole community, or ouiihi we iH>t rather to repicss and alto>;ether annihilate lliem in ord.r that all ii.duHrial work may be onuQned to lari;e f.iotories ? A complete answer to tlii> far reaehiii'j; .(ue^tion will not liure bj at- tempted ; but the folluwiuj; considerations may not bo out of place. Statistics siiow that tlirei; fourtiis of the miioliaiiical power now used in tiie world lias oriu;inale,l within the last tiiirty years; and it has also been computed that one hnndre 1 times iipire work is done by the aid of maeliiiieiy at tlnj pr>. have now been removed, he sees nothing before him buthisday of toil unrewarded save by his weekly wage. It is far otherwise with a man who can be his own employer. He lakes pleasure in, and works with diligenee and foresight at, an oo- cu[)ation IVom which he anticipates a personal ivward lor his own in- du-(rions skill. His Jiitelligence is(|uickeiied by the invention of better methods for the carrying on of his work and in the buying of his own materials and the sale of his own fini.shed products Ho will have an apprentice or two who ought, if they are not already members of his family, to live in his house, and who consectuently, from personal esteem, will lake as keen an interest in the business as he does himself 'ihey ki; iw that they themselves will some day h.\ small employers, so that no detail of the whole organizalioii will escape their vigilance. There is no reason why these people should not have high moral and iiolitical aims ; if only a strong >;oveniinent attends to the just protection of their rights ami property ; and they can then have no possible grounds of eoin|jlaiiit. It would seem theret.ue not cllogieal to draw the conclusion that in a state where small industries flourish there will reign peace, content- ment, order, ami prosperity; that discord imported froih without can lind no root, while discontent'iieiil from within can never arise. 21 Wi' iill koow tlijil till' fiicliiry liaiid ii'ii niiili i o nuiiniDii cilijci't. flinii till' cnntcnliMl ^inull cinplovfr ; uimI tlii^ i.» iIm' ilirrct r'>ult nftlu) ixtnihi'ly uiil'iiv.iMiMlili' I'ciii litioii in wliicli xncli yimill ciiiiiIm^i r« arc plai'iil us rr.,'iiril> tlir nlitniiiiii'.' ut'iiii'i'lmiiifiil pown. A>vi'iiiunlh piij-s nvcr witliinil iniiiliiB..' tliiMii, tlu' fiint rci(ui- ii'iii' lit till' tliiiriiii|'liiviiioii liiiii..' till' p.i-ii'-i«i(iii (it luiitivf '■•iicriu'y ; no tliat Ihoy ^lioitly lall lin|i(li's,.|y iHliiini in a riire in wliicli tlioy aro so lii'uvily lmnilii'.i|i|irii. Ilmv can it 1 iImiwIm wlini it is n iiieinhiTed lliat tliry uiiint. pay rmm 4 to 1)1 liiiii^ nmri' tor jmwir than the iiime tiirtiiiiiiti' capitiili.-t iliir.s ; ami arr at tin; caiiii' liiiio riiiiiiiihii-iij with taxi'8 unil iv^'ulatioiis l>y tin' autlmritii-i li'vinl ii| thr iiiM.scsMim nl' piiiiir iii'ivi'i's in ilif miilst of |iii|Miiiiii" ciiiis ? Siioucr or iator i! niiii^t ciiiiii' that tho ."iiiall cinipinyiT will olnaiii Cor liiuisill thu iiilvaiita'^i's awTiiini; li'imi liir rciinniiiii^iil Msr uf jiowir which an; at pn'suiil the niiiiiopiiy ot thr capitali.-t aloiiu. Tlio {;rcat technical advaiici's recently luade in oloctricity anil in the u.Hc of com) l•c^^s^'ll ail' cviilcnlly |iiiint to thi' spccily Jicciiinplishinent of this ilesirahlc icsnit. Ami in a vny I'rw ilccadcs wi- may confideiitly pi'edict the i'( iiinval fi mn niii- iii niifactiii'ini; cities ufall the waBteful and tioxiuus uas ]iriiiiiiciiiL; | rinic inovi is now uscij ; in their Hliad the eiu|)loyniciil of mine cunveniiiit ami imire eennoniical seeondarv iiiotDrs supplied I'roui iiiaiiis in the strectH which lead the workintr tin d from well conducted and favourdily siluuted powi r -iipply stations, \Vhcn the lime comes, compressed air as mi eiier;;y medinin will be Imiiid to 1)0 an ii'i'epre.ssilile youiiii j;iant demuniliiif; and exacting his duo lecoji;- iiition. My best thanks are due lo Mr. ],n\ B. A. He. of .Vlctiill ("ollei;o for valuable help in coiineetinn with the rstiiiiates of cost ; and to Mr.