﻿226 Dana and Penfield — Undescribed Meteoric Stones. 



Table III. 



Limits. 



Corr. 

 Dr. 



Limits. 



Corr. 

 Dr. 



Limits. 



Corr. 

 C. 



370-04 to 371-95 



+ •05 



382-48 to 384-39 



-•02 



, 370-00 to 37333 



-•06 



371-96 to 372-87 



+ •04 



384-40 to 386-31 



— •03 



373-34 to 376-66 



-•07 



372-88 to 374-79 



+ •03 



386-32 to 388-23 



-•04 



376-67 to 379-99 



-•08 



374-80 to 376-71 



+ •02 



388-24 to 390-15 



— •05 



380-00 to 383-33 



— •09 



376-72 to 378-63 



+ •01 



390-16 to 392-07 



-•06 



383-34 to 386-66 



-•10 



378-64 to 380-55 



•00 



392-08 to 393-99 



-•07 



386-67 to 389-99 



-•11 



380-56 to 382-47 



-•01 



394-00 to 395-91 



— -08 



390-00 to 393-33 



-•12 



As an example of the use of this table, if a line on Dr. 

 Draper's map has a wave-length of 371*95, its true wave-length 

 may be assumed to be 372*00. In like manner 390*00 becomes 

 389 '95. The same readings on Cornu's map would become 

 371*89 and 389*88. 



Applying these corrections to the wave-lengths derived from 

 the map of Dr. Draper, we obtain results which agree very 

 closely with those given by Professor Rowland. The mean 

 difference for the seventy-six lines compared was 0*012, corre- 

 sponding to about one eight-hundredth of an inch upon the 

 Draper map. Probably a remeasurement of the larger differ- 

 ences would still further diminish the average value. No dif- 

 ferences were rejected, the two largest having the values 0*05 

 and 0*06. The mean difference of 0*012 gives a probable error 

 of 0*010, which includes the errors of the two readings and the 

 accidental errors of both maps. We may therefore assume that 

 that the probable error of a wave-length derived from the map 

 of Dr. Draper will not exceed one one-hundredth of a unit if the 

 correction given above is first applied. The minuteness of this 

 quantity is a good illustration of the accuracy attainable from 

 a record obtained automatically by photography. The wave- 

 lengths given on the map of Cornu when corrected in the same 

 way give an average deviation of 0*025, equal to about one 

 one-hundredth of an inch on the map. This is in accordance 

 with the belief of Cornu himself that the probable error of the 

 drawing would not exceed 0*03. 



Aet. XXYII. — On two hitherto undescribed Meteoric Stones ; by 

 Edward S. Dana and Samuel L. Penfield. 



1. Meteorite from Utah. 



In the summer of 1869, the meteoric stone now described 

 was found by Mr. Clarence King in Utah, on the open prairie 

 between Salt Lake City and Echo. It was given by Mr. King 



