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APPENDIX, No. II.
ELEVATION OF PICO RUIVO IN THE ISLAND OF MADEIRA.
Four barometers were employed in this measurement, viz. the two standard marine barometers of the Erebus and Terror, and two portable barometers; the latter were of Newman's construction, with iron cisterns, numbered respectively 94 and 103. The standards were numbered 19 and 20. The corrections for capillarity, the ratio of the capacities of the tube and cistern, and the neutral points, or heights of the mercury, at which no correction was required for capacity, were respectively as follows:—
| 19. | Capillary | + | .012; | Capacity | 120; | Neutral Pt. | 29.922; | Temp. | 65°. |
| 20. | + | .012; | 120; | 29.922; | 65°. | ||||
| 94. | + | .052; | 150; | 30.130; | 55°. | ||||
| 103. | + | .052; | 158; | 30.084; | 60°. |
COMPARISON OF THE BAROMETERS.
The mean of eight readings, taken simultaneously at intervals of ten minutes, gave as follows:—
| Mean Height. | (No. 19.) | 30.172; | (No. 20.) | 30.164; | (No. 94.) | 30.091; | (No. 103.) | 30.142 |
| Capillary. | + .012 | + .012 | + .052 | + .052 | ||||
| Capacity. | + .012 | + .012 | —.001 | + .001 | ||||
| Reduction to 32°. | (72º.3) | —.118 | (71º.6) | —.116 | (69°) | —.099 | (72°) | —.118 |
| 30.078 | 30.072 | 30.043 | 30.077 | |||||
| + .032 | Index. | —.002 | ||||||
| Mean of Standards, | 30.075 | 30-075 | 30-075 | |||||
