REPORT OF THE SECRETARY. 39 



this canal, across which most of the visitors to the Institution have 

 to pass, has become, since the introduction of the Potomac water, 

 the receptacle of the sewage of the city, and is now an immense 

 cesspool, constantly emitting noxious efiluvia prejudicial to the health 

 and offensive to the senses of all who approach the locality. This 

 nuisance, which will continue to increase with the increasing use of the 

 Potomac water, may perhaps be mitigated by placing a gate" at each 

 end of the wider part of the canal, to be closed after high tide and 

 opened occasionally at low water, so as to discharge the contents 

 with a force which would remove, in part, at least, the deleterious 

 deposit. Cut the only effectual remedy, as it appears to me, is to 

 fill up a part of the width of the canal, and convert the remainder 

 into a sewer by covering it with an arch of masonry. This sewer 

 may perhaps be cleared out by flood-gates, as before mentioned, or 

 by anchoring flat-boats at the mouths of the drains, to be removed 

 and emptied when filled. But whatever plan may be adopted, the 

 character and prosperity of the city, as well as the interests of the 

 Institution, are involved in a speedy and efficient effort to remove 

 the evil. The small pecuniary benefit which may result from the 

 canal to the city or to individuals ought not have any weight in the 

 decision of this matter. 



Explorations. — A part of the large collections which have just been 

 described was gathered through officers and other persons attached 

 to the surveying and exploring expeditions sent out by the govern- 

 ment, and another part by expeditions expressly organized for the 

 purpose, under the immediate auspices of the Institution. Among the 

 latter is the expedition mentioned in the last two reports as having 

 been undertaken by Mr. Robert Kennicott, of Chicago. 



This enterprise has terminated very favorably, the explorer having 

 returned richly laden with specimens, after making a series of obser- 

 vations on the physical geography, ethnology, and the habits of ani- 

 mals of the regions visited, which cannot fail to furnish materials of 

 much interest to science. 



The route traversed by Mr. Kennicott was from Lake Superior, 

 along Kamenistiquoy river, and Rainy and Winnipeg lakes, up the 

 Saskatchewan river to Cumberland House ; thence nearly north 

 through a series of rivers and lakes to Fort Churchill on English 

 river, up the latter to Methy Portage, at which point he first reached 

 the headwaters of the streams flowing into the Arctic ocean ; thence 



