me
time, and in the same manner, we should be able to estimate how much of
that OCCASIONAL DISCORDANCE FROM THE MEAN, which attends EVEN THE
MOST CAREFUL OBSERVATIONS, ought to be attributed to irregularity of
refraction, and how much to THE IMPERFECTIONS OF INSTRUMENTS."

In confirmation of this may be adduced the opinion of the late M.
Delambre, which is the more important, from the statement it contains
relative to the necessity of publishing all the observations which have
been made.

"Mais quelque soit le parti que l'on prefere, il me semble qu'on doit
tout publier. Ces irregularites memes sont des faits qu'il importe de
connoitre. LES SOINS LES PLUS ATTENTIFS N'EN SAUROIENT PRESERVER LES
OBSERVATEURS LES PLUS EXERCES, et celui qui ne produiroit que des angles
toujours parfaitment d'accord auroit ete singulierement bien servi
par les circonstances ou ne seroit pas bien sincere."--BASE DU SYSTEME
METRIQUE, Discours Preliminaire, p. 158.

This desire for extreme accuracy has called away the attention of
experimenters from points of far greater importance, and it seems to
have been too much overlooked in the present day, that genius marks its
tract, not by the observation of quantities inappreciable to any but the
acutest senses, but by placing Nature in such circumstances, that she is
forced to record her minutest variations on so magnified a scale, that
an observer, possessing ordinary faculties, shall find them legibly
written. He who can see portions of matter beyond the ken of the rest of
his species, confers an obligation on them, by recording what he sees;
but their knowledge depends both on his testimony and on his judgment.
He who contrives a method of rendering such atoms visible to ordinary
observers, communicates to mankind an instrument of discovery, and
stamps his own observations with a character, alike independent of
testimony or of judgment.

SECTION 2. ON THE ART OF OBSERVING.

The remarks in this section are not proposed for the assistance of
those who are already observers, but are intended to show to persons not
familiar with the subject, that in observations demanding no unrivalled
accuracy, the principles of common sense may be safely trusted, and that
any gentleman of liberal education may, by perseverance and attention,
ascertain the limits within which he may trust both his instrument and
himself.

If the instrument is a divided one, the first thing is to learn to
read the verni