[53] FISHERIES OF THE UNITED STATES. 1207 



McDonald fish-way. 



Photograph of the falls at Fredericksburg, Va., showing tbe Mc- 

 Donald fish-way in position behind the abutment. Size, 8 by 

 10 inches. Fredericksburg, Va., 1882. 2,244. U. S. Fish Com- 

 mission. 



McDonald fish- way. 



A photograph of the Falls at Fredericksburg, Va., showing the Mc- 

 Donald fish-way in position behind the abutment. Size, 30 by 

 40 inches. Enlarged by electric light from an 8 by 10 nega- 

 tive. Fredericksburg, Va., 1882. 2,244. U. S. Fish Commis- 

 sion. 



V. — Purification of streams. 



6. Cleansing- residuum from manufacturing establishments, 

 etc., before it enters the rivers. 



Gas-works. 



Drawings illustrating the method of purifying the residuum of gas- 

 works before allowing it to pass off into the river. Description 

 of apparatus, with letter of explanation to Prof. S. F. Baird, by 

 J. R. Shotwell. 



