XXIV LETTER TO THE SECRETAEY. 



In the bibliographical appendix the bibliography of the Yellowstone 

 National Park is brought down to February, 1883. Bibliographies of 

 Iceland and New Zealand and lists of authorities for the tables of thermal 

 springs (in the second part) are also given. The mineralogical appen- 

 dix contains a list of minerals of the Park and analyses of several of the 

 great variety of igneous rocks found within its limits. 



Tbe topographical map of the Park, by Mr, Henry Gannett, has 

 already been referred to. It is an excellent example of his accuracy 

 and skill in this kind of work, both in the field and in the office. Mr. 

 Gannett was one of the most faithful and energetic members of the 

 Survey for several years, and his reports upon a variety of topics were 

 of a high order. His geographical report in this volume is a model of 

 conciseness as well as critical accuracy. So far as this subject is con- 

 cerned, but little more is left to be done. All the elevations have been 

 examined with great care, and may be regarded as substantially cor- 

 rect. The descriptions of the mountain ranges and drainage are minute, 

 and the entire report will furnish much valuable matter for a guide- 

 book of the Park. The maps of the geyser basins are as accurate and 

 complete as will probably ever be needed. 



The chromo-lighographic and lithograi^hic illustrations in this report, 

 by Thomas Sinclair & Son, are finely engraved and do credit to that 

 enterprising establishment. 



It remains now for me to express my cordial thanks to all the assist- 

 ants that have so long and so ably aided me in the work that is now 

 closed. I part with them with real regret. Should my health ever be 

 restored, much additional matter now partially prepared may be given 

 to the world. 



Very respectfully, your obedient servant, 



F. Y. HAYDBN. 



To the Hon. Secretary of the Interior. 



