proceedings. 87 



Miscellaneous. 

 (Names of Donors are in Italics.) 



Bonaparte, Prince Eoland — Le Glacier de l'Atetsch et le Lac 

 de Miirjelen. Le Premier Etablissement des Neer- 

 landais a Maurice. The Author, Paris. 



Bourke, Capt. John G., U.S.A. — Mackenzie's Last Fight 

 with the Cheyennes : a Winter Campaign in Wyom- 

 ing and Montana The Author, Washington. 



Hayter, Henry Heylyn, c.m.g., &c. Three Papers read before 

 the Australasian Association for the Advancement 

 of Science ; Sydney, 1888, Melbourne, 1890. 



The Author, Melbourne, 



Naturwissenschaftliche Wochenschrift , Band n., No. 15, Band 



in., No. 3, 1888. The Publishers, Berlin. 



Report of the Central Park Menagerie, New York, for the 



year ending 1889. Br. W. A. Conlclyn, New York. 



Topinard, Dr. Paul — La Societe, FEcole, le Laboratoire et le 



Musee Broca 1890. The Author, Paris. 



Trubner's Record. Third Series, Vol. i., Parts vi., No. 248, 



1890. The Publishers, London. 



THE THEORY OF THE REPETITION OF ANGULAR 



MEASURES WITH THEODOLITES. 

 By G. H. Knibbs, l.s., Lecturer in Surveying, Sydney University. 



[Read before the Royal Society, N.S.W., August 6,1890.'] 



The system, in using a theodolite, of repeating the measure of an 

 angle, that is of continuously adding it on the graduated circle, 

 may be advantageously employed whenever the errors of reading 

 that circle, or the errors of its graduation, are large as compared 

 with those due to imperfect direction of the telescope on the objects 

 between which the angle is included. In discussing the theory of 

 this system, it is proposed to exhibit its intrinsic character, to 

 investigate the errors peculiar to it, to supply a criterion of its 

 precision, and to indicate the manner in which it may be made to 

 contribute the most accurate results. 



Method of Repeating. 



Repetitional measures may be thus described: — Setting the 

 verniers or microscopes to read zero,* the telescope is directed by 



* The commencement of the process is expressed in this way for the 

 sake of simplifying the discussion. The necessary modifications, when 

 the verniers are not primarily at zero, are too obvious to require explicit 



statement. 



