2,2 CARNEGIE INSTITUTION OF WASHINGTON. 



and the 6o-inch equatorial reflector now available, photographic, spectro- 

 graphic, and visual observations may be made; and these may be supple- 

 mented by and compared with observations made in the laboratory, where 

 conditions as to temperature and pressure of the gases observed can be con- 

 trolled and measured. 



Many publications from the Observatory have appeared during the year. 

 Most of these, necessarily preliminary publications, have been printed in the 

 Astrophysical Journal. 



An important asset in the plant of the Solar Observatory is the road lead- 

 ing to the summit of Mount Wilson. This is about lo miles long on an 

 average grade of lo per cent, increasing in some places to more than 20 

 per cent. It has served admirably for the safe transport of the parts of the 

 60-inch telescope up the mountain. Some of these single parts weigh as 

 much as 5 tons. 



After repeated failures, the glass manufacturers of St. Gobain, France, 

 have succeeded in casting a suitable disk for the 100-inch mirror of the 

 Hooker telescope. This disk is now en route to Pasadena and the work of 

 grinding it should soon be begun. 



The activities of this department have extended during the year to a wide 

 range of localities, and correspondingly satisfactory progress has been made 



Pj , toward a complete magnetic survey of the globe, 



l^errestrial The ship Galilee, chartered from her owners at San 



Magnetism. Francisco in July, 1905, completed her third cruise on 



the Pacific Ocean in Ma}^ of this year and was then returned to her owners. 

 This cruise was started at San Diego, California, on December 22, 1906, 

 and covered a distance of about 35,000 nautical miles. At the beginning 

 of the present fiscal year the Galilee had just set sail from Jaluit for Port 

 Lyttleton, New Zealand. Arriving at this port December 24, she proceeded 

 to Callao Bay, Peru, and thence to San Francisco, where she arrived on May 

 21, 1908. Altho the ship encountered many delays and dangers in this 

 long voyage, invaluable magnetic data were obtained. Twenty primary 

 and twenty secondary land stations were established and numerous observa- 

 tions of the three magnetic elements (of declination, dip, and intensity) were 

 made at sea. In the three cruises made by the Galilee a total of more than 

 60,000 nautical miles has been traversed, securing thus from this source 

 alone a fairly good magnetic survey of the Pacific Ocean. 



Experience with the Galilee has demonstrated the practicability of secur- 

 ing on the ocean measures of the earth's magnetic elements of nearly the 

 same precision as those made on land. Mid-ocean measures appear, indeed, 

 to be of greater value than those on land, since the latter are more often 

 subject to local anomalies, and the former are directly applicable to the needs 

 of navigation. The same experience has demonstrated the necessity of hav- 

 ing a ship specially designed for ocean magnetic work and provided with 



