[T]his Fifth Edition is required to meet the demand of a somewhat wider class of students than those for whom the Lectures were originally intended. … - George Biddell Airy

Complete knowledge of every theoretical and instrumental detail can only be obtained by those who will devote... a large portion of their lives; but sound knowledge of the principles... can be obtained by the reasonable efforts of persons possessing common opportunities for general knowledge.

In the application of the ordinary principles of geometry and trigonometry to such Astronomical measures... it may sometimes be expedient to resolve the process into several successive steps, and these steps may perhaps require different kinds of treatment. But... all are simple and within ordinary comprehension, and the only complexity arises from the circumstance that the student may find it necessary to have a clear view of several such steps at once...

In conversing with persons who are not officially attached to Observatories or in other ways professionally cognizant of the technicalities of practical Astronomy but who nevertheless display great interest... these persons appear to regard the determination of measures like those of the distance of the Sun and Moon as mysteries beyond ordinary comprehension... [and] when persons well acquainted with the general facts of Astronomy are introduced into an Observatory, they are for the most part utterly unable to understand anything which they see...
The measure of the Moon's distance involves no principle more abstruse than the measure of the distance of a tree on the opposite bank of a river. The principles of construction of the best Astronomical instruments are as simple and as closely referred to matters of common school-education and familiar experience, as are those of the common globes, the steam engine, or the turning-lathe; the details are usually less complicated.