This book presents a detailed analysis of
some highly significant astronomical instruments designed in the German states
during the 19th century: Carl Steinheil's
astronomical drawing-board, Karl Friedrich Zöllner's astro-photometer
and Oswald Lohse's astro-camera.

Based on these instruments, the author shows how, by rebuilding these instruments and practising
with them, significant historical insights
can be gained. The author demonstrates
how observers interacted with new instrument designs and how different
observers using new types of instruments
could reach agreement. The newly founded Astronomische Gesellschaft enabled a
rapid distribution of these new instruments together with the communication
of observations.

This book argues that in the new discipline of astro-photometry,
scientific practice eventually overcame theoretical doubts.