Royal Astronomical Society. 141 



effects, Mr. Maclear took another and a more advantageously related 

 system, and found a result agreeing almost exactly with his former 

 one. Still the effect of attraction at the southern end only remained 

 imperfectly compensated, and that at the northern not at all. Mr. 

 Maclear then resolved to extend the arc to the length of the usual 

 European ones, to place the terminal stations in the best positions 

 which could be found, to swing the pendulum on every mountain, 

 and to fix the positions of all such points as might be useful in future 

 land or coast surveys. This work has occupied him during the course 

 of the years from 1843 to the present time, and it is not yet com- 

 pleted. Either of four stations may be used independently at the 

 extreme southern end of the arc — the Royal Observatory, Lacaille's 

 Observatory in Cape Town, one on the mountain Zwarte Kop, 

 twenty miles south of the observatory, and one on Cape Point, the 

 extreme south-west of Africa. The most northern station is on the 

 Khamiesberg, giving a total length of about A\ degrees, with an in- 

 termediate astronomical station on the top of Heer Logiments-berg. 

 From the extreme south to the middle station two sets of triangles 

 are formed ; from thence to the northern, one and a part of another. 

 From the Royal Observatory extends an eastern chain of triangles, 

 for the settlement of the position of Cape l'Aguillhas and the measure- 

 ment of an arc of parallel. The sides of the triangles vary from 50 

 to 90 miles. The country to the north of Khamiesberg is now under 

 examination, to try the feasibility of carrying the triangulation up 

 to a station at which a perfectly unexceptionable latitude can be ob- 

 tained. The physical difficulties of the northern part of the trian- 

 gulation have been enormous. The houses at 20 miles distance 

 from each other — the natives themselves imperfectly, and sometimes 

 not at all, acquainted with the mountains through which the sur- 

 veyors had to explore difficult passes in most inclement weather — 

 the difficulty of finding water, and the scanty quantity of it when 

 found — the irksomeness and danger of carrying the instruments up 

 ascents which a free and active man can only surmount with diffi- 

 culty — the endurance of all temperatures, from sand in the plains at 

 140° of Fahrenheit to ice and sleet on the heights — and the possi- 

 bility of return being cut off by the gathering of snow in the ravines, 

 — present a picture far from inviting, and form a measure of the re- 

 solution of Mr. Maclear and his assistants, as well as of the strength 

 of the principle which carried them into those wilds. The Society 

 will join the Council in hoping that their success may be equal to 

 their desert. 



The President (Capt. W. H.Smyth, R.N.) then addressed the Meeting 

 on the subject of the award of the Medal, as follows : 



The Report, Gentlemen, which you have just heard, has acquainted 

 you that your Council have awarded the Medal of this Society to 

 Mr. Airy, the energetic Astronomer Royal, for his reductions of the 

 Planetary Observations made at Greenwich between the years 1 750 

 and 1830, by which an immense magazine of dormant facts, contained 

 in the annals of the Royal Observatory, are rendered available to 



