ON MAPPING THE SURFACE OF THE MOON. 303 



on the moon's surface." At the time of the appointment of the Committee, 

 I had made 291 series of observations, which were commenced as early as 

 January 6, 1860. 



During the year, between the Meetings of the Association at Bath and 

 Birmingham, I have lost no opportunity of increasing the number of observa- 

 tions, and have made 124 series, which are equivalent to 124 nights of 

 observation. These observations amounted to 416 series at the time of the 

 Meeting at Birmingham ; and, with 33 made since, now amount to 449. 

 The whole are of various kinds, including physical examinations of several 

 portions of the moon's surface, particularly of the crater "Plato," every 

 crater, mountain, ridge, plain, or other feature that had been the subject of 

 observation being distinctly specified in the observations. Numerous micro- 

 metrical measurements for the magnitudes and positions of objects are also 

 included. The whole of these observations are in process of being examined, 

 reduced, and classified, and the results entered in Form No. 3. 



The series of observations between January 5, 1860, and September 22, 

 1863, amounting to 176, were made with two telescopes. The one most 

 extensively used in London was the Sheepshank's Telescope No. 5, lent by 

 the Council of the Koyal Astronomical Society expressly for the purpose of 

 lunar researches. The diameter of the object glass is 2-75 inches. It is 

 furnished with three powers, is mounted on a tripod, and has vertical and 

 horizontal motions in altitude and azimuth. The observations not made 

 with this instrument were made during various visits to Hartwell with the 

 Equatorial of 5-9 inches aperture. 



Early in January 1863, the Council of the Royal Society voted a sum of 

 money for the construction of a telescope with an object glass of 4| inches 

 diameter, under the superintendence of Warren De la Rue, Esq., suitable 

 for the work in which I was then and am still engaged. This was completed 

 in September 1863, and has since been employed in the observations, stated 

 visits during the period that has elapsed between June 1863 and September 

 1865 having been made to Hartwell, at Dr. Lee's request, for the purpose of 

 continuing the observations with the Hartwell Equatorial. 



.At the time of the appointment of this Committee, I had drawn up preli- 

 minary forms for the insertion of various data appertaining to objects on the 

 moon's surface, a large amount being scattered over the works of Schroter, 

 Lohrmann, and Beer and Madler. It was then, and still is, my intention to 

 increase these data by observation, and enter them in Form No. 3, each 

 object, as before mentioned, being designated by a symbol. When the Asso- 

 ciation met at Bath in 1864, 386 separate objects had been entered in the 

 preliminary Forms j 62 of these have since been transferred to Form No. 3, 

 which, with 399 entered independently, make 461 objects entered in Form 

 No. 3, the total number of objects now catalogued being 785*. 



Early in December 1863 I conceived the idea of forming a catalogue of 

 lunar objects, as I had met with considerable difiiculty in recording many, 

 especially the smaller features, in such a way as readily to identify them 

 afterwards. At that time I had accumulated a number of observations* first, 

 of the crater ' Plato ' and its immediate neighbourhood, and afterwards of the 

 N.W. portion of the Mare Imbrium, including all the mountains which are 

 scattered over its surface, which have been named the * Teneriffe' Mountains, 

 to commemorate « an astronomer's experiment,' as recorded in Professor Piazzi 

 Smyth's work entitled < Teneriffe.' 



In the course of my observations several remarkable features of the moon's 



* Now augmented to 1002. 



