New York City, Feb. 15, 1905.
To the Editor:
—Your editorial comment (February 11, page 477) on the so-called red-light treatment of smallpox is eminently sound and just. In Dr. Schamberg's original article he stated that he used "ruby-colored" glass, but failed to state that he had tested the same for actinism either spectroscopically or photographically. The old style of genuine pot-metal ruby is, I believe, no longer to be found in trade—at least I have not succeeded in getting any, even from sources that supplied me some years ago. All of the so-called ruby glass that I have examined admits an abundance of actinic light, running up even to the blue of the spectrum. The negative experiences of Dr. Schamberg, therefore, have no weight with me and I much prefer to rely on the positive evidence afforded by Finsen and others. The idea, however, of excluding light in the