Stargazing: Past and Present

Having in the previous chapter dealt with some of the pioneer work, we come finally to consider some of the applications which in the last years have occupied most attention.

When we dealt with the astronomical instruments of Hipparchus, we saw that although the astrolabe which that great observer used was the germ of our modern instruments, the time...

We have already gone somewhat in detail into the construction of the transit circle, which is almost the most important of modern astronomical instruments. We then referred to t...

Before we go on to the use and various mountings of telescopes, the optical principles of which have been now considered, a few words may be said about the materials used and th...

First we may touch upon the physical observations made with the eyepiece alone—star-gazing, in fact. The Sun first claims our attention: our dependence on him for the light of d...

The gain to astronomy from the discovery of the telescope has been twofold. We have first, the gain to physical astronomy from the magnification of objects, and secondly, the ga...

We have next to say something about the principles on which the use of the spectroscope depends; if we look through one we can readily observe how each particular ray of light p...

The connection between the transit instrument and the transit clock is so intimate that either is useless without the other. In the one case we should note the passage of a star...

We are now, then, in full possession of the stock-in-trade of the modern astronomer—the telescope, the clock, and the circle,—and we have first to deal with what is termed astro...

Some sciences are of yesterday; others stretch far back into the youth of time. Among these there is one of the beginnings of which we have lost all trace, so coeval was it with...

In the telescope as first constructed by Galileo there are two lenses, so arranged that the first, a convex one, A B Fig. 37, converges the rays, while the second, C D, a concav...

We have now described the method of obtaining and keeping true Greenwich time by means of transit observations, and the next thing is to distribute it either by controlling or d...

We have now to speak of the methods of using these spectroscopes for the purpose of astronomical observations. For a certain class of observations of the sun no telescope is nec...

It is difficult to give the credit of the invention of the telescope to any one particular person, for, as in the case of most instruments, its history has been a history of imp...

Leaving behind us the results of the researches of Ptolemy, who succeeded Hipparchus and whose methods have been described, and passing over the astronomy of the Arabs and Persi...

In previous chapters we have considered the lessons that we can learn from light—from the vibrations of the so-called ether—when we put questions to it through various instrumen...

Having now obtained the lenses and specula we come, in order to complete our consideration of the purely optical portion of the subject, to the question of mounting these lenses...

It will have been gathered from the previous chapter that the perfect circles nowadays turned out by our best opticians, and armed in different parts by powerful reading microsc...

In the addition of chemical ideas to astronomical inquiries, we have one of the most fruitful and interesting among the many advances of modern science, and one also which has m...

Among the astronomers of antiquity there are two figures who stand out in full relief—Hipparchus and Ptolemy. The former, “the father of astronomy,” is especially the father of...

One branch of observatory work is that of determining the relative _magnitude_ of stars, the word magnitude being of course used in a conventional sense for brightness. There ar...

As the equatorial is _par excellence_ the amateur’s instrument, and as in setting up an equatorial it is important that the several adjustments should be correctly made, they ar...

The ancients called the places occupied by the sun when highest and lowest the Solstices, and the intermediate positions the Equinoxes. The first instrument made was for the det...

In the introductory chapter we referred to the introduction of photographic records of astronomical phenomena as marking an epoch in the development of the science. In the last...

The point we have next to determine is how we can utilise the properties of reflection for the purposes of astronomical observation. Many admirable plans have been suggested. Th...

We have now dealt with the refraction of light in general, including deviation and dispersion, in order to see how it can assist us in the formation of the telescope; and we hav...

We have considered the telescope as a combination of an object-glass and eyepiece in the one case, and of a speculum and eyepiece in the other; that is to say, we have discussed...

One of the great advantages which astronomy has received from the invention of the telescope is the improved method of measuring space and determining positions by the use of th...

We have now gone down the stream of time, from Hipparchus to our own days. We find now enormous telescopes which enable us to see and examine celestial bodies lying at distances...

The process used should therefore be the most rapid attainable; any work on photography will give a number of processes of different degrees of rapidity, but a process that suit...

At one of the very earliest meetings of the Royal Society, the difficulties of mounting the long focus lenses of Huyghens being under discussion, Hooke pointed out that all diff...

In former chapters we have described the transit circle as it now exists as the result of the thought of Tycho, Picard, Römer, and Airy. This, though the fundamental instrument...

We have now considered the mounting and adjustment of the equatorial, be it reflector or refractor. If of large dimensions it will require a special building to contain it, and...