THE HOSPITAL LIGHTING QUESTION.

Dominion, Volume 4, Issue 1008, 24 December 1910, Page 3

THE HOSPITAL LIGHTING QUESTION.

is the' enclosure sent.ta : . WORLD",". : sth, 1910—n. 559 . / QUESTIONS AND 'ANBWEKSM' ' ' "FOR COMPiT?rqn-M i OP COSTS OF DIFFERENT LIGHTS. ■ Jl) Compare cost 0f..-' lighting with'' ordinary invertedj incandescent .gas, at showil'-^r tho ! Isand - 'and electricity, ' ' 1. ?.? the ,P nce at w l»ch the latter ! OuoL fi supp^ed to give' the same light.- . Quota hgures in support, showing method ' vari»tT n „ g f at rt-° f :I, ; ghtin S all the ' ™ + l? iv electric lamps, especially ' la , m .P s ' ' f « . Which -aJ'.': nf nilt 11 Egln , e f r claims a consumption Ot only 15 wa tts per candle. (2) Show anj- disadvantage pertaining, to various ' '■ sj stems as regards •• maintenance. (3) state commercial 'value of free water ... power , over any other power for gcceratmg electricity.—B.6.C. ' m ?thbd of comparing the' cast of lighting with any two illuminants, wnere the consumptions of the different 7. agents are known, and the prico is ■ round ■■ from the formula—C-wxp+r C is the cost .in' any-convenient unit— • usually pence are taken—of 1000 hours' us; of the particular lamp, w is the niim-; V.' ber of watts, or the number -of cubic : feet of gas per hour, required by the '" lamp, p is" the price per thousand cubic ieet or per unit,'and vis the cost.of 'renewing .the lamp or the mantle, , or any ?£? er , P art 'he apparatus, during 'the ; 1000-hours. The formula is 'obtained!bri': taking the .number of j watts, or tho-njim-bsr of cubic feet required per -. tiplyiug by the cost .per unit,, or per thousand cubic fcet, v -and dividing iby ' 1000, as representing tho. 1000 watr-liuurs of a Board of Trade electrical unit aud the 1000 cubic, feet of gas ujian which the , - chargs. is based. The figure 1000" appear- '.- ing in both numerator, and denominator, ' cancels out. . Applying the .formula to the case quoted, and-allowing two mantles, _at cost of -3d. each," and the race mentioned, ss. sd. per thousand cubic feet, and allowing, a consumption of 3 cubio feet., per hour for a GO-candle lamp, the ' formula'works out thus—Cs 3x65+6 - 201 d.' Taking the. formula as above, . C = wxp+ r , -.if. will .be seen : that it may '■ be .written C-r-wxp, and, therefore, - ; C-r . p=—• This formula will enable w us to find the price at which electric current must be sold for any. given elec-■' - trie lamp, taking current at a given rate, to equal the cost by gas .at the. figure' ' given in . the question. Applying tho formula to the .'metallic filament incandescent lamp, and allowing one lamp ,at ' ~5. Gd.. for. the. 1000. hours, the - figures - 201-30 171 ' ' i:. come out p —-2.28 d., or, say, '..' ; 75 ' - 75 ' ' ' 2{d. per Board of Trade unit. : ' ■ i In. the ; above 'we have allowed-- the consumption of electricity by the metallic ' filament lamp at the rate at which it is 1 .- 1 mm ..usually taken,- 'viz., 1J watts - per ' : - i- , I ' her€ ar P 'amps on the market i w " ,c jj a consumption of only-1 witt ! ' per candle is claimed. AVe have also - allowed 1000 hours as the life of a '60- 1 ! candle metallic? filament 'lamp.-' "B Or C " : can discount, these'figures as much-as'his " '-' experience will have shown him. On the ' - other hand, gas lighting-engineers-claim ' ji v mantle furnishes a 60canate'light for a consumption of 2,cubfo ■' ' feet l>srhour. If that figure is taken it • v brings the >. price at which-the electrio current must be supplied, with the metal- " lie--filament- -lamp, down-to -und'r -13d ' per unit. , " '

arc lamp, the consumption of electricity per candle-power is in the neighbourhood, of 0.5 watt. In c om e calculations we,made a short..while sinco ; - we found the cost of arc lamps, worked out 6ii the" formula given above, raueed ■ from .£6 10s. to £1 55.. per 1000 hours, as 1 " against -high-pressure ♦ gas lamps, . <£3 ss. • to i,6 10s. ■ ■ (2) The metallic filament lamp' and the incandescent gas mantle are both subject to tke disadvantage that, the light given .lessens .with* age,- and in'both cases the lessening'of the light, depends upon the working conditions.'. With .the incandescent electric- lamp, variations of / pressure, such as are very- common fin. ■ town service mains, have a very. bad effect.- -The-disadvantage-of-the:arc lamp, ■ over the high-pressure incandescent- gas• lamp is .the fact' thSftKe. arc lamp re-' quires a", certain amount of attention. With enclosed arc lamp,. however, this.has. been,reduced to a minimum. j.v, (3) The commercial value of free water-- -, power for generating electricity depends entirely upon'the conditions under which ' the • wateivpower is obtainable, jthe prin- - cipal condition■ being the distance from.'.:, the point" of distribution. . Water-power saves coal, but as against;the saving of' coal there is the interest.upon.the trans-•' mission line, and the cost of the upkeep of-the line. - If . the water-power is at a ; considerable distance from the town-to ba supplied, for instance, the interest and upkeep may more than equal the . cost of the coal -that is saved. 'A. striking instance of this is the case of the .Victoria Balls, on the Zambesi. • Thsy are a very great distance from-the K-and,-and the proposal, that was made, some little while back to utilise them for'.supplying-' power to the R-and, in place of burning , coal there, though the local coal is very p-cor, was practically, laughed out of court. On the other hand, again,'the power .of Niagara is being utilised at Buffalo, some 22 miles'away, for lighting - and power."