636 



SCIENCE. 



[X. S. Vol. XXI. No. 538. 



The port of Benzert, on some maps called 

 Bizerta, is located about 50 miles northwest 

 from Tunis. The harbor facilities of Benzert, 

 which are naturally very good, have been of 

 late years very much improved by the French 

 government by dredging and by protective 

 works in order to make it the location of an 

 extensive naval station. As a harbor it is 

 very commodious and accessible to large ves- 

 sels. It is connected with the railway system 

 and is the terminus of a submarine cable. 



The port of Tunis is inferior in harbor 

 facilities to either Benzert or Bona, and need 

 not be considered as a landing-point. 



From this region the shadow path proceeds 

 southeastwardly across the desert into Egypt, 

 where it crosses the river Nile in the neighbor- 

 hood of Assouan. The total phase occurs here 

 something more than one hour before sunset. 

 The shadow leaves the earth in central Arabia. 



Some of the points to which the attention 

 of astronomers will be directed may be briefly 

 stated as follows : 



(a) The Relative Position of the Sun and 

 Moon at the Time of the Eclipse. — The an- 

 gular distances between the centers of the sun 

 and moon may be derived from observations 

 of the four contacts, by visual or by photo- 

 graphic methods. This necessitates an accu- 

 rate determination of the latitude and longi- 

 tude of each observing station, which neces- 

 sarily consumes a large amount of time and 

 labor, and demands the use of a special instru- 

 mental outfit. 



Since the position of the moon is so well 

 cared for by meridian observations, and since 

 the additional data derived from contact ob- 

 servations is small in quantity and of a dis- 

 tinctly lower grade in quality, it follows that 

 contact observations should be considered of 

 secondary importance compared with the work 

 in other lines. 



(h) The Search for Intra-mercurial Planets. 

 — Hitherto photographic searches for intra- 

 mercurial planets have been made with incom- 

 plete apparatus or have been interfered with 

 seriously by clouds. 



In this eclipse it is highly important that 

 a photographic search be prosecuted at two or 



three widely separated stations with very com- 

 plete apparatus. 



(c) 2*/ie Corona. — The corona should be pho- 

 tographed with long focus lenses to obtain 

 large scale pictures of the inner corona, and 

 with short focus lenses for pictures of the 

 corona as a whole embracing its ultimate ex- 

 tensions. It would be well to locate the 

 parties at a number of widely separated sta- 

 tions, and Professor Campbell, director of the 

 Lick Observatory, suggests the use of lenses 

 of a standard aperture and focal length, say 

 five inches aperture and forty feet focus, to 

 furnish data for studying changes in the 

 corona as the shadow sweeps over the earth. 



The work on the corona should be consid- 

 ered of the highest importance. 



(d) Spectrum Work. — All the facilities 

 available to the astronomy of the present day 

 for photographing the spectrum of the revers- 

 ing layer, the chromosphere, the prominences 

 and the corona, should be used to their utmost 

 capacity in the coming eclipse. On account 

 of lack of light the slit spectroscopes used will 

 be confined to a few special problems, leaving 

 the great bulk of the work to be executed by 

 objective spectrographs, using either gratings 

 or large prisms. 



It is also suggested that a number of spec- 

 trographs be employed to determine the ac- 

 curate wave-length of the principal coronal 

 line. 



The spectrum work should be considered of 

 equal importance with that on the corona. 



(e) Photometrij; Shadow Bands. — Of sec- 

 ondary importance are photometric observa- 

 tions and observations of the character of the 

 so-called shadow bands. 



if) Polariscopic Worh. — Polariscopic and 

 polarigraphic work should be well cared for 

 with increased facilities for accurate work. 



Polariscopic work should be considered of 

 importance nearly equal to that on the corona 

 and the spectrum. 



(<;) Meteorology. — The meteorological con- 

 ditions existing at the several stations, espe- 

 cially during the progress of the eclipse, 

 should be observed by means of the best self- 

 recording instruments. 



