32 REPORT OF THE SECRETARY. 



at a cost not to exceed eighty thousand dollars, to be paid for from time 

 to time as appropriations may be made by law; and the said Com- 

 missioners are authorized to construct said sewer, where necessary, 

 across lands belonging to the United States: Provided, That after the 

 construction of said sewer the. excavated portions of said lands shall 

 be restored to their original condition from the appropriation herein 

 j>rovided for. 



In accordance with this law the Commissioners of the District pro- 

 ceeded to survey a course for an intercepting sewer along Eock Creek 

 within the limits of the park. While the engineers in charge of the 

 work have conducted their operations with discretion and courtesy the 

 circumstance has brought forcibly to my attention the desirability of 

 clearly defining the authority of the park officials in cases where it 

 becomes necessary for employees from other branches of the Govern- 

 ment to carry on work within the park. There is a very real danger 

 that engineering operations may be conducted so as to injure the ani- 

 mals and destroy the natural beauties of the region, making it impossible 

 to " restore the land to its original condition." As conflict of authority 

 would seriously embarrass the work it would be well if in future 

 cases of this kind the law should specifically provide that operations 

 should be conducted under such reasonable regulations of the park 

 authorities as may insure, as far as practicable, the safety of the ani- 

 mals and the preservation of the natural features of the park. 



Immediately subsequent to the date of this report one of the most 

 interesting and valuable animals of the park (a sea lioness) died from 

 fright, due to an explosion without warning caused in the progress of 

 the work just referred to. 



ASTRO-PHYSICAL OBSERVATORY. 



The investigation of the infra-red spectrum has been continued in the 

 Astro-physical Observatory during the past year with increased energy, 

 and I am glad to be able to say that if only provisional results have 

 yet been published, which, like those of last year's report, are intended 

 merely to show the character and progress of the work, it is because 

 the means of giving greater exactness are constantly growing, so that 

 the result it is now hoped to present will be given with the aim of a 

 still higher standard of precision; an aim which it may be trusted will 

 be considered a legitimate cause for the delay in the appearance of the 

 final results. 



I refer for all details to the more extended report given later, but, 

 briefly, it may be stated that a larger number of holographic records 

 has been obtained than in any previous year, and that these continuous 

 observations have been accompanied by further improvement in the 

 apparatus, a higher standard of accuracy, and a nearer approach to 

 the completion of the research; but that they have also shown beyond 

 a doubt that the limit of accuracy which is desirable can never be 



