my father's. It was the use of photography in stellar measurement. As is
well known to photographers, in 1871 Dr. R.L. Maddox used gelatine in
place of collodion from which innovation rose the present system of dry
plate photography. My father had always felt the greatest interest in
the use of photography in astronomy. He was acquainted with the splendid
work done by Chapman for Rutherford, New York, in his careful and
exquisite photographs of the moon. As early as 1850 Whipple of Boston
made photographs of the stars.

It was, however, the incomparable advantages, furnished in speed, by
the dry plate photography which made my father realize early as anyone,
the boundless possibilities thus opened in human attainment for the
penetration of the Sidereal firmament. He had made a great number of
photographs at Irvington, and the photographic laboratory was a charming
illustration of my father's ingenuity and precision. At Mt. Cook we
enjoyed a marvellously clear atmosphere for work of this sort, and
amongst the first thoughts of my father was to provide the most
satisfactory means for the continuance of our stellar photography.
Besides our visual telescope we had a photographic telescope which was
used, instead of connecting the visual lens on one and the same
instrument, as in the Lick Observatory.

The innovations introduced by photography have revolutionized the
processes of stellar measurement. Instead of the laborious task of
measuring the stars through the telescope, the photographic plate can be
studied at ease as a correct and identical chart of the heavens and the
results thus obtained placed at the disposal of astronomers. My father
appreciated this and amongst his numerous projects of scientific
usefulness the preparation of photographs of the stars fully occupied
his mind.