Academy of Sciences] 

 No. 13] 



BIOGRAPHY 



meter of cushion replaced the running meter as a convenient unit of reference, though a square 

 meter of open window was taken as the final standard. The general relation of these two units 

 is brought out in the following passage: 



For the purposes of the present investigation, it is wholly unnecessary to distinguish between the transfor- 

 mation of the energy of the sound into heat and its transmission into outside space. Both shall be called ab- 

 sorption. The former is the special accomplishment of cushions, the latter of open windows. It is obvious, 

 however, that if both cushions and windows are to be classed as absorbents, the open window, because the more 

 universally accessible and the more permanent, is the better unit. The cushions, on the other hand, are by 

 far the more convenient in practice, for it is possible only on very rare occasions to work accurately with the 

 windows open, not at all in summer on account of night noises — the noise of crickets and other insects — and in 

 the winter only when there is but the slightest wind; and further, but few rooms have sufficient window surface 

 to produce the desired absorption. It is necessary, therefore, to work with cushions, but to express the results 

 in open-window units. 



Having no money, 7 in the early years of his investigation at least, for building structures 

 such as he would like to study, Sabine was obliged to depend on chance opportunities to measure 

 the influence of different building materials. Sometimes these opportunities were of a kind not 

 likely to recur, and we should sadly underestimate the merit of his achievements if we failed to 

 note the swiftness and finality of his action in such cases. 



This is his story of one ; evidently the new rooms described might never be empty again : 



Through the kindness of Professor Goodale, an excellent opportunity for securing some fundamentally 

 interesting data was afforded by the new botanical laboratory and greenhouse recently given to the university. 

 These rooms— the office, the laboratory, and the greenhouse — were exclusively finished in hard-pine sheathing, 

 glass, and cement; the three rooms, fortunately, combined the three materials in very different proportions. They 

 and the constant-temperature room in the physical laboratory — the latter being almost wholly of brick and 

 cement — gave the following data: 



Office^ - 



Laboratory -.. -- 



Greenhouse- 



Constant-temperature room 



Area of 

 hard-pine 

 sheathing 



127.0 



84.8 



12.7 



2.1 



Area of 

 glass 



Area of 



brick and 



cement 





 30 

 85 

 124 



Combined 



absorbing 



power 



8.37 

 5.14 

 4.64 

 3.08 



This table gives for the three components the following coefficients of absorption: Hard-pine sheathing, 

 0.058; glass, 0.024; brick set in cement, 0.023. 



Another case of conditions difficult to obtain is described as follows: 



Next in interest to the absorbing power of wall surfaces is that of an audience. During the summer of 1897, 

 at the close of a lecture in the Fogg Art Museum, the duration of the residual sound was determined before and 

 immediately after the audience left. The patience of the audience and the silence preserved left nothing to be 

 desired in this direction, but a slight rain falling on the roof seriously interfered with the observations. Never- 

 theless, the result, 0.37 per person, is worthy of record. The experiment was tried again in the summer of 1899, 

 on a much more elaborate scale and under the most favorable conditions, in the large lecture room of the Jefferson 

 Physical Laboratory. In order to get as much data and from as independent sources as possible, three chrono- 

 graphs were electrically connected with each other and with the electro-pneumatic valve controlling the air 

 supply of the organ pipe. One chronograph was on the lecture table, and the others were on opposite sides in the 

 rear of the hall. The one on the table was in charge of the writer, who also controlled the key turning on and off 



7 The following letter gives some indication of that severe scrupulosity which was inveterate in Sabine: 



Uarvard University, 



Cambridge, November 12th, 1897. 

 Dear Mr. Sabine: Your explanation of November 3rd about your expenditures in making the investigation which Mr Hooper and I asked you 

 to make is very far from being satisfactory. You have made sufficient progress to be able to prescribe for the Fogg Lecture-room, and you are going 

 to make that prescription. What the Corporation wants is to pay all the costs to this date of that investigation, not of those experiments only 

 which certainly contributed to the result, but of all the experiments made with that object in view which Mr. Hooper and I set before you. Unless 

 you enable the Corporation to do this by rendering an account of your expenditures, you leave the Corporation in the position of haviDg engaged you 

 can work in their interest which not only cost you much time and labor, but also cost you money. It seems to me that on reflection you will per- 

 ceive that this is not a suitable relation for the Corporation to be left in with one of its assistant professors. You will of course be at liberty to 

 continue the investigation at your discretion, and at your own charge; but up to this time all charges ought to be paid by the Corporation, 

 including the travelling expenses, admission tickets, and the purchase of instruments. These expenses do not require any justification— they are 

 matters of course in such an inquiry. 



Very truly yours, ■ 



(signed) Chaeles W. Eliot 



Professor W. C Sabine 



