o.—la.

APPENDICES.

APPENDIX No. 1. REPORT ON OBSERVATIONS FOE LATITUDE, MADE WITH A ZENITH TELESCOPE, FOR THE YEAR ENDING 30th JUNE, 1885. Mr. Adams to the Subveyob-Genebal. Gawler Downs, Ist July, 1885. Dueing the month of July, 1884, I was engaged in Wellington in preparing for publication Tables 1 to 7 in connection with my report on the determination of the difference of longitude between Sydney and Wellington. On the 18th and 25th July I took observations to determine the altitude of Mount Cook Observatory and Kaukau Trig. Station. I also wrote a paper on the determination of time, latitude, and azimuth with an 8-inch transit theodolite. On the last day of July, 1884, I left Wellington for Auckland in the " Hinemoa," and during the remaining eleven months I have been engaged observing latitudes and azimuths with the zenith telescope, visiting in succession Auckland, Mangonui, Tauranga, Gisborne, Napier, Nelson, and Burnham. I need not here recapitulate the description of the zenith telescope, which will be found in the Annual Survey Eeport for 1882-83, but will give a description of an iron stand which I had constructed in Auckland, to be used in those places where it was not convenient to erect a stone pedestal. This stand is made wholly of iron, and is in shape a truncated cone, being 30 inches high, 16 inches in diameter at the top, and 21 inches in diameter at the bottom. The sides have thus a batter of 1 inch to afoot. The stand is constructed chiefly of sheet-iron, about one-sixteenth of an inch thick; it has a cast-iron flange round the top and an angle-iron flange round the bottom. There are two circular holes," 5 inches in diameter, opposite each other, one-third of the distance from the top, which serve as handles to move the stand, and also to admit light to the interior. The weight of the stand is 571b. A cast-iron triangle, weighing 71b., fits on the top of the stand, and has grooves to receive the three footscrews of the zenith telescope. By means of three capstan-headed screws the triangle can be readily fixed in any position, and thus when observing horizontal angles the zero may be changed in a few seconds. I have used the stand at three stations only—namely, Gisborne, Nelson, and Burnham; stone •pedestals being used at all the other stations. At Auckland I observed on the transit pier used by the American transit of Venus party in 1882, in the domain, and I had a small wooden building erected over it as a temporary observatory. At all the other stations I used a frame tent which I had made in Auckland. I have found it well adapted for taking observations in, and it has already stood some severe gales. On the 14th March, 1885, the Survey Observatory, Mount Cook, Wellington, was dismantled, and the instruments packed up and left at the head office. In the selection of pairs of stars I have confined myself exclusively to Stone's Cape Catalogue of 12,441 stars, and have always found sufficient stars within 10° of the zenith. I think I may say that the degree of accuracy obtained has been quite satisfactory, as the probable error of the latitudes only averages "-05, or 5 feet on the ground, while the probable error of the azimuths is always less than one second of arc. In the following tables, rj = the average difference of each observation from the mean; r = the probable error of a single observation ; r o == the probable error of the final result.

Table A. Observations for Latitude, 1884-85.

I—C. IA.

Locality. Date. Station. Alt. No. of Obs. Latitude. Eemarks. r o Auckland ... 1884. Aug. and Sept. American Transit of Venus Station, 1882 20a Domain Feet. 258 135 o / it 36 51 50-58 •93 •76 // •066 Stone pilla: VTangonui... Cauranga.. Sept. and Oct. Nov. and Dec. 186-4 68-2 115 122 34 59 35-79 37 40 57-31 •66 •68 •57 •57 .05 .05 Stone pilla: Stone pilla: 1885. 428 330-7 470-7 219-3 139 147: 158 197 38 40 38-04 39 28 43-52 41 16 14-82 43 36 48-54 •68 •561 •72! •62 •57 •47 •61 •52 •05 •04 •05 ■04 3-isborne ... Sf apicr kelson 3umham ... January February April May and June 108 60 Botanical Hill British Transit of Venus Station, 1874 and 1882 Iron stand Stone pillai Iron stand Iron stand