Proceedings, &e., for 1883. 141 



Mr. Ellery said that these polyzoa had been obtained by dredgings 

 near Queenscliff . This paper contained a complete list of Victorian 

 species of Retepora. Dr. MacGillivray exhibited some specimens. 



Mr. Ellery exhibited a new personal equation instrument, in 

 which the exact moment of the passage of a mark representing a 

 star across the middle of the field of vision could be accurately 

 'recorded electrically on a chronograph. An observer using the 

 instrument records in a similar way his observation of the time of 

 passage; the difference between the two records represents the 

 personal equation of the observer. 



October llth, 1883. 



Present, the President (in the chair) and 32 members and associates. 



A ballot was taken for the election of the following gentlemen, 

 who were duly elected : — Mr. H. T. Tisdall as member, Mr. W. H. 

 Gregson as member, Mr. R. Schafer as an associate. 



The following gentlemen were introduced to the meeting as new 

 associates : — Mr. W. H. Brock enshire, Mr. E. C. Rennick, Mr. B. A. 

 Smith, Mr. G. Wight, Mr. C. G. V. Williams, Mr. A. M. Grant, 

 Mr. L. L. Murray, Mr. J. H. Dunlop, Mr. A. J. Noall, Mr. A. E. 

 Phillips. 



Mr. Ellery described and exhibited a new form of Darkfield 

 illumination micrometer for astronomical purposes. He said that 

 wherever micrometers with wires or webs were used in telescopes for 

 astronomical purposes, it was necessary to obtain artificial illumina- 

 tion of these wires. For general purposes the simple illumination of 

 the field of the telescope in the ordinary way was sufficient, in which 

 ^ase the wires appeared as black threads on an illuminated ground. 

 But in case of observing very faint objects, and in some of the more 

 delicate observations, such a mode of lighting renders faint objects 

 invisible. It was, therefore, necessary to devise an illumination in 

 which the field should be quite dark, and the wires rendered faintly 

 but distinctly visible. Many micrometers for this purpose had 

 been constructed, but he had seen none thoroughly satisfactory, 

 except such as were too unwieldy and cumbersome. The one he 

 exhibited had lately been constructed in the Observatory workshop, 

 and appeared to possess all the qualities requisite, without being 

 either too expensive or too cumbersome. In describing the instru- 

 ment he said : — 



"This micrometer is of a somewhat novel form. As far as the 

 micrometer box, parallel wire frames, screws, &c, are con- 

 cerned, it resembles the ordinary parallel wire micrometer 

 of the German form. The principal frame which carries the 



