Magnetic observations made at Colaba Observatory, Bombay [Mumbai], India Daily observations made at hourly intervals at the Colaba Observatory. Commencing with horizontal force magetometer readings [pp.3-16]; declination magnetometer [pp.17-30 and pp.59-69]; and vertical force magnetometer [pp.31-57]. With mean readings of the declination magnetometer [p.86]. 1-31 March 1842