1902. 



FORESTRY AND IRRIGATION. 



20: 



the Association of Official Agricultural 

 Chemists. It is not so very long ago 

 that the American tanner or extract man- 

 ufacturer considered a chemical analy- 

 :sis to possess no value whatever, and 

 preferred to buy or sell on the basis of 

 the density of the material. This state 

 of affairs was chiefly due to erroneous 

 methods of anal3'sis and the lack of uni- 

 formit}' even when the same method 

 was followed. Through consistent 

 effort and study on the part of a number 

 of chemists interested in the subject, 

 this has been changed, and at least 75 

 per cent of the tanning extracts and 

 materials found on the American mar- 

 ket to-day are sold on the basis of an 



analysis by the official method. At the 

 last meeting of the association it was 

 agreed generally that this method is 

 now practically perfect, and it was there- 

 fore decided to take up the study of 

 other analytical methods applicable in a 

 tannery, the object being to eliminate 

 the sources of error now existing. The 

 ultimate aim of all this work is the 

 adoption of an international method for 

 the analysis of tanning materials which 

 will be a service to the American impor- 

 ters, as the European chemists are now 

 using a method which gives to an ex- 

 tract or tanning material a valuation 

 from I to 2 per cent higher than the 

 official method. 



THE HYDROGRAPHY OF COLORADO. 

 By a. L. Fellows, 



U. S. Geological vSurvev. 



THE relations existing between hy- 

 drography and forestry are inti- 

 mately bound together. Hydrography 

 being, generall}^ speaking, the study of 

 water in all its characteristics and uses, 

 it logically follows that the relationship 

 between the two sciences is so close that 

 they are almost inseparable. 



It is within the province of the United 

 States Geological Sur\'ey to examine 

 into all the inorganic resources of the 

 country, and one of the greatest of such 

 resources is, as all will admit, our water 

 supply. So great is the importance of 

 this branch of the investigations that 

 labor along these lines has been dele- 

 gated to a separate division, namely, the 

 Division of H^-drography of the U. S. 

 Geological Survey, of which Mr. F. H. 

 Newell is at the head. Its work is the 

 study of all problems connected with 

 the existing supply, whether derived 

 directl}^ from rainfall or from the run-off 

 of drainage basins, whether these prob- 

 lems bear upon amounts available for 

 use or upon the use itself. 



In the pursuit of information along 

 these lines a number of gaging stations 

 have been established throughout the 

 country generally, but more particularly 



where the call for such investigations 

 has been the greatest. In Colorado, for 

 example, petitions have been sent in 

 from nearly every part of the state, ask- 

 ing that investigations be carried on 

 with a view to ascertaining the amount 

 of water available for irrigation, either 

 by diversion directl}" from streams or by 

 means of storage. In accordance with 

 these requests, about thirty-five gaging 

 stations have been established and are 

 being operated at the present time. 

 Petitions have been sent in from Maine 

 to California, more from some states 

 perhaps than from others, but enough 

 from all to indicate the great demand 

 for definite information concerning our 

 available water supply and the uses to 

 wdiich it may be put. By some states 

 appropriations have been made for the 

 purpose of cooperating in the work with 

 the Division of Hydrography, the basis 

 of agreement being usually that the 

 Sur^-ey will, if it is in its power, devote 

 the same amount of money that the 

 state itself devotes to the investigation. 

 In many cases the amount appropriated 

 b}' the state has been exceeded ; in some 

 cases the states have appropriated noth- 

 ing, although they have requested that 



