372 



SCIENCE. 



[N. S. Vol. XVI. No. 401. 



should be toward the blue end, and the 

 opposite eifect would show itself in examin- 

 ing stars in the direction from which we 

 are moving. Campbell has examined manj' 

 stars in the northern sky, and soon will go 

 to Chile to continue his observations. The 

 final result wiU give us both the point 

 among the stars toward which the solar sys- 

 tem is going and the velocity. These facts 

 being known, the astronomer may be able 

 in the future to calculate when the sun and 

 his family wiU come into dangerous proxim- 

 ity to other great systems in space. Such 

 thoughts need not worry us as the time is to 

 be reckoned in thousands of years ! 



The spectroscope applied to sun, planets, 

 stars, nebulffi, comets and meteors, has given 

 us a splendid record, and the present cen- 

 tury is full of promises of greater results. 



To-day in all great observatories photog- 

 raphy is used to obtain permanent records 

 of sun, planets and stars, etc. When we 

 study the photographs taken, we are im- 

 pressed with the fact that our sensitive 

 plates, when exposed to an object, will show 

 on development more and more, depending 

 on the time of exposure. The startling in- 

 formation is obtained that after from ten to 

 twenty-five hours or more exposure we can 

 obtain a photograph which wiU show us 

 what we never can hope (as far as we now 

 know) to see in our telescope! Let us give 

 our imaginations free rein, and we may 

 dream of getting only general information 

 with our eyes, but by the use of sensitive 

 plates in photography we may make amaz- 

 ing discoveries all around us of things the 

 eye cannot see. 



In conclusion let me quote the words of 

 one of onv ablest workers in celestial pho- 

 tography : 



" If we were asked to sum up in one word 

 what photography has accomplished, we 

 should say that observational astronomy has 

 been revolutionized. 



"There is to-day scarcely an instrument 



of precision in which the sensitive plate has 

 not been substituted for the human eye; 

 scarcely an inquiry possible to the older 

 method which cannot now be undertaken 

 iipon a grander scale. Novel investigations 

 formerly not even possible are now entirely 

 practicable by photography, and the end is 

 not yet. 



"Valuable as are the achievements al- 

 ready consummated, photography is richest 

 in its promise for the future. Astronomy 

 has been called the 'perfect science'; it is 

 safe to predict that the next generation wiU 

 wonder that the knowledge we have to-day 

 should ever have received so proud a title." 



Columbia Univeesitt. "■ ^- Rees. 



AMERICAN ASSOCIATION FOR THE AD- 

 VANCEMENT OF SCIENCE. SECTION 

 I, ECONOMIC AND SOCIAL 



SCIENCE. 



In the absence of Hon. Carroll D. 

 Wright, Commissioner of Labor, Mr. John 

 Hyde, Statistician of the Department of 

 Agriculture and Vice-president of the sec- 

 tion for the Denver meeting, presided over, 

 the Section. On the afternoon of June 30 

 the vice-presidential address of Mr. Hyde, 

 on 'Some Economic and Statistical Aspects 

 of Preventable Diseases,' was delivered. 

 The address will be piiblished in full in 

 Science. Meetings for the reading of 

 papers were held on the morning and after- 

 noon of July 1, the morning and evening 

 of July 2 and the morning of July 3. The 

 meeting on the afternoon of July 1, at 

 which the papers of Messrs. Alvord, Pow- 

 ers, Beal and Lazenby were read, was held 

 jointly with the Society for the Promotion 

 of Agricultural Science. 



Titles and abstracts of the papers read in 

 full are as follows: 

 Economic Situation of Pittsburgh : Geokge 



H. Anderson, Secretary of Pittsburgh 



Chamber of Commerce. 



Greater Pittsburgh, comprising Alle- 

 gheny County, ranks fourth in population 



