( 427 ) 
INDEX. 
Abney’s Level, 8 
Acceleration Table, 423; explanation of 
table, 230 
Adjustments of sextant, 17-18; of the 
box sextant, 22 
Adjustments of the transit theodolite, 
26-33 
Admiralty Manual of Scientific In¬ 
quiry, 7 
Altitude of a heavenly body, to compute 
the, description and example, 191-194 
Altitudes, determination of, by boiling- 
point thermometer, example and 
tables, . 209-213 ; by barometer or 
aneroid, example and tables, 214 218 
Amplitude, to find the sun’s, 93 
Aneroids, ordinary form, useful for 
differential observations, but unreli¬ 
able for absolute heights, should be 
observed in conjunction with boiling- 
point thermometers, 4; Mr. E. 
Whymper’s work on, referred to, 14; 
form best suited to traveller, should 
be tested at the National Physical 
Laboratory, measurement of heights 
with, 14; advantage claimed for Wat- 
kin aneroid for obtaining heights, 15; 
determination of heights by, example 
and tables, 214-218 
Aneroid, Watkin Mountain, Mr. E. 
Whymper’s experiments with, 5 
Angle subtended between thumb and 
middle finger, 53 
Angles subtended by a 10 ft. rod, at 
distances from 50 to 1500 ft. table, 
280-281 ; explanation, 222 
Angular distance between two terrestrial 
objects, to measure, with a sextant, 
83 ; angular distance between the 
moon and sun, star or planet, to 
measure the, 183-184 
Apparent time described, 150 
Arc into time, table for converting, 422 ; 
explanation, 230 
Arithmetical complement of a logarithm, 
to find, 223 
Artificial horizon, folding roof or 
George’s, recommended, 2; different 
forms of: roof, Capt George’s, black- 
plate, 22 ; how to clean the mercury 
for, 22 ; substitutes in case the 
artificial horizon should be broken, 
24; to observe the altitude of the 
sun using an, 138 
Astronomical observation, section on, 
135-208; importance of, for correct¬ 
ing route surveys, 135 
Augmentation of the moon’s semi¬ 
diameter, table, 425 ; explanation 
of table, 231 
Azimuth, to find error of compass by 
sun’s, example, 208 
Barometer, Aneroid (see Aneroids) 
Barometer, mercurial, Fortin’s pattern, 
should be made to read low enough 
for great altitudes, Prof. Norman 
