out what things you have most taste for, as they are what you should study most; but get a general knowledge of all the sciences.  Whatever else you learn, don’t forget mathematics and the sciences more immediately deduced from them, (at the head of which stands astronomy,) if you have any love of truth—­and if you have not, you have none of your mother’s blood in you.  Mathematics are the foundation of all truth as regards practical science in this world; they are the only things that can be demonstrably proved; no one can dispute them.  In geology, chemistry, and even in astronomy, there is more or less of mere matter of opinion.  For instance, in astronomy we do not know for certain what the sun or stars are made of, or what the spots are on the sun, and a few details of that kind; but the main mathematical principles cannot be disputed.  The distance and size of the sun or of any of the planets can be proved; the length of their days and years, and even the weight of the matter of which they are composed.  Such things will probably appear to you impossible, if you have read nothing of them; especially when you hear that the sun is ninety-five millions of miles off, and that the planet Neptune, which is the farthest known planet from the sun, is at such a distance that the light of the sun takes about five hours to reach it; that is, the sun is actually five hours above the horizon before the people there see it rise.  Its distance is 2850 millions of miles, and the sun as seen by them is not larger than Venus appears to us when an evening star.  And although this planet is so distant that it can only be seen with large telescopes, they can not only compute its distance and size, but also the mass of matter of which it is composed.  But you will find all this thrown into the shade by the way in which it was discovered.  As I may be telling you what you know already, I will merely state, that from observed perturbations in the course of the planet Uranus, it was supposed that another planet was in existence beyond it; and two competitors set to work to calculate its size, situation, etc.  The result was, the discovery of this other planet within a few minutes of the place pointed out by them, and its size, etc., not very different from what they estimated it at.  But besides this, astronomy includes matters more intimately mixed up with our everyday affairs.  In the Nautical Almanacs, which are constructed for several years in advance, the situations and nearly everything connected with the different planets are calculated for every day in the year, and can be found, if required, for any minute in any day you please, for 10,000 years to come.  Also the eclipses of the sun or moon, with the exact moment at which they will commence or end, at any spot on the earth; the exact portion eclipsed, or, in fact, anything about it you like to mention for any given number of years in advance.  Not only this, but you can find the eclipses of Jupiter’s