THE PROGRESS OF SCIENCE. 



667 



vard Observatory photographs of the 

 spectrum were obtained on February 22 

 and February 23. On these dates the 

 spectrum was not the typical one which 

 we have learned to expect for Nova?, but 

 instead was of the Orion type, consist- 

 ing of a strong, continuous spectrum 

 crossed by dark lines. Between Febru- 

 ary 23 and February 24, however, a 

 wonderful transformation took place. 

 Since the latter date the spectrum has 

 consisted in large part of the bright and 

 dark bands which are characteristic of 

 the spectra of Nova?. 



The first new star of which there i9 

 authentic record appeared 134 B. C. 

 During the two thousand years which 

 have since elapsed, nineteen more have 

 been noted, making about one per cen- 

 tury. This can by no means represent 

 the true number of such stars which 

 have appeared during that time. Doubt- 

 less only a few of the brightest have 

 been seen. Of the twenty on record, 

 thirteen belong to the century just 

 ended, and six to the last decade, five of 

 which were found on Harvard photo- 

 graphs. Of all the stars visible in the 

 largest telescopes, not more than one in 

 ten thousand can be seen by the naked 

 eye. Thirteen of the Nova? were bright 

 enough to be seen by the unaided vision. 

 At the same rate for the fainter stars, if 

 we may assume that the number of 

 Nova? corresponds in some degree to the 

 whole number of stars for the different 

 magnitudes, several thousand new 

 stars must have escaped observation 

 during each century. No entirely satis- 

 factory explanation has yet been given 

 of these remarkable objects. From 

 dark, or at least from extremely faint 

 bodies, they suddenly blaze up and 

 slowly fade away. Any theory which 

 aims to explain the phenomena must at 

 least account for certain leading facts. 

 The increase of light is very sudden and 

 very great. The decrease is slower and 

 sometimes irregular, but no collision 

 can have occurred such as would change 

 a solid body into a gaseous, otherwise 

 ages, not weeks, would be required for 



the cooling. The spectrum is generally 

 composite, composed of bright and dark 

 lines or bands. The bright bands are 

 displaced toward the red, the dark 

 bands toward the violet. If this sep- 

 aration is due to the relative motions 

 of two gaseous masses, the velocities 

 concerned appear to exceed those found 

 elsewhere in the universe. The Nova 

 sometimes remains as a permanent tele- 

 scopic object with the spectrum of a 

 planetary nebula. The problem might 

 be somewhat simplified 'f the broaden- 

 ing of the lines could be due to the 

 Zeeman effect from the presence of a 

 strong magnetic field. It appears prob- 

 able that the phenomena are due either 

 to some outburst in the dark world it- 

 self, or else to the collisions of a solid 

 dark world passing through a dense me- 

 teor swarm. It is to be hoped that a 

 discussion of all the materials, which 

 will be obtained at the different ob- 

 servatories during the next few weeks, 

 may serve to formulate a theory of new 

 stars which will receive the general ap- 

 proval of the scientific world. 



The investigations on agricultural 

 soils which are being conducted in this 

 country are probably unsurpassed in 

 quality and extent by those of any 

 country, unless it be Russia, where 

 a very systematic and extensive line of 

 investigations, including a survey and 

 classification of the soils of the whole 

 country has been in progress for a num- 

 ber of years. The work in this country 

 has been carried on mainly by a number 

 of the agricultural experiment stations 

 and the Division of Soils of the National 

 Department of Agriculture. The report 

 of the Field Operations of the Division 

 of Soils for 1899, by Prof. Milton Whit- 

 ney and a number of his assistants, late- 

 ly issued, is a report of progress in sur- 

 veying the soils of the United States. 

 During the year areas aggregating 

 about 720,000 acres were studied in the 

 field and mapped. This work has been 

 largely confined to localities in New 

 Mexico, Utah and Colorado, and a spe- 

 cial feature made of studies on the ac- 



