5" 3- 7.3 



PREFATORY NOTE. 



The Bulletin of tlie Survey was commenced in 1874 for the purpose of 

 giving to the world, more rapidly than through the Annual Eeports, the 

 vast amount of new material which was constantly accumulating under 

 the auspices of the Survey, and, in most instances, demanding prompt 

 publication. When the first and second numbers were printed, it was 

 not expected that it would continue long, or be issued with any regu- 

 larity, hence the paging is not consecutive ; but its success was so great 

 that it commenced the year 1875 as a regular serial, and it will be seen 

 that six numbers have been issued of about five hundred closely-printed 

 octavo pages, with twenty-six pages of maps, sections, and other illus- 

 trations, with table of contents and full index. It is suggested that the 

 entire eight numbers for 1874 and 1875 be bound in one volume as vol. 

 I ; and the table of contents and index have been prepared with that 

 idea in view. During the year 1876 the Bulletin will be continued, the 

 paging will be consecutive, and the illustrations numbered in their order 

 so far as it is possible to do so. 



Most of the articles in the Bulletin will not be reprinted, especially 

 the more technical ones : but those of a i)opular character will appear 

 again in the Annual Eeports, usually much enlarged and improved. 



It is to be hoped that the numbers already issued and distributed,^ 

 both in this and foreign countries, have been preserved, inasmuch as 

 several of them are already out of print and will not be re issued. 



