by the illuminometer within ten per cent. Surely, you are glad to have something to tell you within ten per cent if you cannot estimate it within fifty. PROFESSOR HOUSTON: I do not think it necessary to carry on this discussion very much longer, though there are one or two points I should like to discuss briefly, in answer to the objections that have been so happily raised by gentlemen who have preceded me. As to the permeability of the secondary illuminator, as questioned by Mr. Haskins : Yes, there may be some question as to its being more permeable to light of a certain frequency than of another. I think the explanation by Mr. Kennelly of the methods we adopt in calibrating the instrument will remove any objection that may have existed in that direction. As to the question so ably raised by Professor Thomson, it is unfortunately true that there are limitations to all our senses; but these limitations are by no means restricted to the eye; they apply to all our senses; and, to a certain extent, the objections that the Professor has so pertinently brought out as limiting the use and applicability of our instrument, must necessarily apply to any instrument of physical research that can be employed. As to how long one should wait until the eye gets rested after reading the instrument, I think the answer is clear; he should wait until he can read the test object within the instrument. He cannot get the required condition in a moment. It may require two or three motions of the slide shutter, so that his eye will be exposed once or twice to an increasing and decreasing illumination; and by the time he can read the test object, I think his eye would be a fairly normal eye. In the same way this will answer, I think, the objections to the time legibility, as to whether we can see a thing rapidly or not. After all, the use of this instrument only requires that a person shall be able to do what his training has taught him to do since he first opened his eyes in the world, to be able to see an object with fair distinctness-that is all. There is very little judgment required, except that he must determine whether or not he can see well enough to do a certain thing; that is, to read. I know that this instrument may seem objectionable to some because it makes experts too cheap. Now, I, personally, being in that business myself, might object to that; but I want to say this: I think that as soon as you put an instrument of this type in the hands of the public, you make the public experts, and, to a certain extent, just as reliable to determine roughly a question that heretofore has required delicate measurement and long training, viz., the effectiveness of any illumination. Do you not see that under these circumstances the question of the integrity of experts becomes a matter of very little importance? It is not only a few who can reliably make true measurements, but anybody can do it roughly. I think that is all that need be said about the subject. As to color-blindness, this does exist; but but I question very greatly whether the doctors, in their interest in physiological research or their willingness to say that certain people on the railroads should not be in charge of locomotives, may have permitted their judgments to be warped to some extent. I do not believe that color-blindness exists to the degree stated. If it does, this instrument is not limited to the use of five or six people, but may be used by practically anybody. In this way the actual facts can be known. MR. SEELY: I move that a vote of thanks be extended to Messrs. Houston and Kennelly for their valuable paper. (Carried.) 66 DEAR SIR: I beg to advise that the Cleveland Telephone Company has placed two telephones at your disposal for the use of the delegates to the convention; one located in the Bureau of Information, Room 101, Hollenden Hotel, the other in the rear of Convention Hall in the small room at the west side of the stage. "Through the courtesy of the Long-Distance Company, we are also enabled to offer delegates the free use of the long-distance wires to any points reached by them, between the hours of 5 P. M. and 9 A. M., standard time. It was also announced that the Cleveland Electric Railway Company extended to the the delegates the courtesies of the street cars during their stay in the city. On motion, the convention adjourned until Wednesday morning. ORDER OF BUSINESS. WEDNESDAY, February 20th. THIRD SESSION, IO. 15 A. M. I. Report. Finance Committee. 2. Paper-"The Correct Method of Protecting Electric Circuits." By W. E. HARRINGTON. 3. Paper-" Large Arc Dynamos." By C. N. BLACK. FOURTH SESSION, 2.30 P. M. I. Topic" How to Light Large Cities.' 2. Paper "The Monocyclic System." By DR. LOUIS |