The bones of Comstock House may be made of old-growth redwood, but the soul of the grand old place is its light. The daylong sunshine that fills the south and east bedroom windows; the warm green pastels that wash through the stained glass an hour before sunset; the twilight orange glow from soft electric lights in evenings.

The home at night could seem gloomy because the rooms never have the bright illumination favored in modern houses. It's one of those tradeoffs for living here, just as the hydronic radiator system denies you the quick gratification of a blast of warmth from the furnace on a chilly morning. Not having the option to flick a switch and turn midnight into noon is no great loss, in my mind; having deep shadows in some places makes the house feel quieter overall, even if a video or music is loudly playing in another room. Or, to reprise a theme often mentioned here, an old house is comfortable only if you understand and embrace the systems inherent.

LEFT: The entrance hall gas-electric chandelier, with three electric lights and three gas jets

Evening lighting would have been slightly different in 1905. Although we're using lightbulbs of approximately the same luminance as in that period (much more about that below), the Oates family also could light the gas on some chandeliers and wall sconces. The bright flame from the gaslight - which was coal gas, not natural gas - would have cast hard chiaroscuro shadows, which in conjunction with the gentler, dimmer electric bulbs, would have produced a harmonized "blending of the many lights," as described in a newspaper item about a 1906 party in the house.

Having fixtures that were both gas and electric was more of a necessity than luxury when Comstock House was designed in 1904, and probably every home in town had mantle lamps or some other means to augment the electric service. The reason is simple: The power company couldn't keep the lights on. The "juice" for Santa Rosa came from the Colgate hydroelectric power station in the Sierra foothills, and the lines often failed - sometimes for days on end - when the weather was less than perfect. An alternative source of illumination was also practical because electricity was very expensive. Adjusted for inflation, electricity cost 25 times more than it does today.

Although we have table and floor lamps around the house to make particular living areas brighter, we've sought to maintain the original brightness and color of light from wall and ceiling fixtures. In this period, incandescent bulbs were typically lower wattage than common today, and the filaments were usually thicker. The combination meant that the filament ran much cooler, thus emitting an orange glow instead of today's brighter blue-white.

It's possible to buy reproductions of old style bulbs (here's one source), but at nearly $18 each, lighting the whole house with them would be prohibitively expensive. Another product on the market, marketed as a means of extending the lifetime of incandescent lamps, is the “Button." These are adhesively attached to the base of modern light bulbs to reduce the wattage, allowing the filament to run cooler. The Button has a diode inside, which only allows normally alternating current (AC) to flow one way, literally cutting the power available to the lamp in half. The recommended way to use the Button would be to install a higher wattage bulb than is needed; since the lamp would then run cooler, it will last longer, saving the consumer money by replacing the bulbs less often. For our purposes, we use lower wattage modern bulbs which the diode cuts down further, taking the output into the range that was commonly used in the early 20th Century.

If the Button was the easy solution, accurately defining the problem was more of a trick. Namely, how bright were incandescent lightbulbs in 1905, really? As far as we can tell, no one in modern times has waded into this research, so the analysis below is original; corrections and other interpretations are most welcome.

Judging from multiple sources from that period including the trade journal "Illuminating Engineer," the typical lightbulb for home use was sixteen candle power, at around three watts per candle. This would mean that average bulb was a little less than 50 watts. Thus you can screw a modern 40-50W bulb into a socket and have that "Ragtime Era" look, right?

Wrong. The old bulbs were considerably less efficient than a 50W incandescent bulb today. Modern bulbs use tungsten filaments, which didn't come into common use until just before the World War I years. In 1905, lamps still had carbon filaments, which radiated more heat than light. The carbon filaments also burned much cooler than tungsten: 1300 vs. 3410 degrees centigrade. To compare the efficiency of old and new filaments, refer to the graph on this page from the 1912 "Cyclopedia Of Architecture, Carpentry, And Building" which shows the logarithmic efficiency curve for carbon filament bulbs. If plotted on the same graph, the much hotter tungsten filament would be shown to produce about EIGHT times the amount of light for the same wattage.

Another way to look at the problem is to compare modern and old lumens, but there's the little snag that early electricians compared watts per candle, not lumens per watt. Fortunately, a 1907 paper in Illuminating Engineer states that the standard bulb had the efficiency of 3.3 lumens per watt. By that calculation, the modern incandescent is about FIVE times brighter.

Whether the old lights were precisely 12 or 20 percent as bright as today's bulb doesn't really matter; once in use, the bulbs also rapidly lost efficiency as the inside of the glass blacked with soot. And then there was the issue of unreliable voltage; the more juice the brighter the light, and electrical transmission standards were notoriously unreliable. All that you can say with assurance is that home electric lighting was much, much dimmer than it is today.

Finally (!) our conclusion: the average 50W lightbulb in 1905 would be the equivalent to 7-12W today. We vary between both. For the newel post (pictured here) we are using the Button to cut the wattage from a modern 11W bulb by half, using a lower wattage at that location because it's functionally a night light. For wall sconces and chandeliers, we have 25W modern bulbs with the Button. In either case, the overall effect is the same welcoming orange glow that you should have seen when walking through the door on a fine evening in 1905.


I enjoyed reading your story in the PD and the posts and pages of your site. I can only imagine the scope of your restoration or this lovely old home; it's truly a labor of love. It's heartening for me to see one of our communities grand historical gems nurtured through the years instead of allowed to fall into a disrepair beyond restoration. Bless you for taking on the work. I look forward to watching your progress.
Cynthia Bailey MD

March 1, 2010 at 9:39 AM  

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