The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1888-05-09
The EIectric-Light Bids.

20 the Editor of the Indianapolis journal.
The bids for eleetriclighting having been
made public, it is probably within the bounds of
propriety to discuss them publicly.
The Journal does not state number Of lamps
contemplated by the Thompson Houston Com
psny's bid. but judging from amount of their
gross bid they intend to furnish about the same
number as the other companies.
The specifications prepared by the city en-
eineer require plant that will '.insure the
lighting of streets. avenues, alleys and public
grounds as we'll a. they are now lighted. Do the
propositions conform to that requirement.
The territory now liehtad is about $40 acres.
now served with light by 2,644 gas and 241 oil
lamps. Each company proposes to substitute
about $50 arc and 100 incandescent electric lights
for the Same purpose. Discussing the arc
lights y themselves, l find that the average
area to be served by each 10 about 81 acres,
equal to 4l3, $50 feet; the average distance apart
then. Of the lights will be tho square root Of
this. or CAB feet But it is proposed to light
about 400 squares each street intersection,
thus placing say $50 of the lamps one-tenth OF
q mile or 52S feet ap art. The other 100 lamps
will therefore be ION the average) l.o45 feet
apart.
Now the radius of the effective lighting area
OF 2.000candle power arc light is 200 feet; ie.,
such lamp will effectually light circle whose
diameter 10 400 feet, when hung a. the height
above the ground 80 feet required by the
specifications Simple subtraction soon shows
that the lamps 52S feet apart win leave portion
OF each square 128 feet long insuficently
lighted, and those 1,045 feet apart, space of
645 feet, much of which will be ir total dark
ness. And on the residence streets, where there
is line Of dense shade trees along each curb.
the sidewalks, for seven to eight months each
Jear, will be in almost total darkness their en-
tire length. The ANAL numoer Of incaudescent
lamps (lOO) would indicate that, in order to
mako them go around" they are to be placed
at alley Intersections hence the streets will de-
rive no benefit from these lamps at all.
The city OF Columbus. o., has one street
lighted with Thompson Houston lights
about four hundred feet apart. Il being
a business street without trees, the lighting il
quite satisfactory. The city OF Lafayette,
Ind, is lighted throughout by Brush lamps $50
feet apart in the business district and 600 feet
more apart in the remainder of the city. and it
has been found necessary TO use the gas lamps
wherever they occur at intermediate points.
The sidewalks bordered by trees are absolutely
dark except where gas lamps have been relight-
ed
Many will ask why are such large power
lamps of so little long distance effectivenessf
The answer is that the intensity of light di-
minishes proportionately to the square of the
distance, and the effectiveness even more owing
to alterations of the atmosphere; hence, while the
2,000candle power light will, At distance OF 200
feet, afford light of about the intensity Of
average moonlight at 300 feet the light will be
proportionately four ninths. or less than half
and at $40 feet, four-twentysevenths. or about
one-seventh. How do the people of the out
lying residence districts like thsl For they al
ready are better served with light on the pres
ent system. II the requirement Of the speci-
fcations means. as it should mean, that no spot
now lighted shall receive less light than at
present afforded. then is it not plain that the
proposals are made in direct violation Of the let
ter and spirit Of that requirement.
Err civil Euo;naap