Objects, Advantages, And Pleasures Of Science.

tance , is nearly 1200 times larger ' than this Earth . Our distance from the Sun is above 92 millions of miles , but Jupiter is 475 millions , and Saturn 872 millions of miles distant from the Sun . The rate at which the Earth moves round the Sun is 66000 miles an houror nearly 140

, , times swifter than the motion of a cannon ball ; and the planet Mercury , the nearest to the Sun , moves still quicker , about 106 , 000 miles an hour . We , upon the Earth ' s surface besides being carried round the Sunmove round the Earth ' s axis by

, the rotatory or spinning motion which it has ; so that every 24 hours we in England move in this manner nearly 14 , 000 miles ( persons living on the equator about 24 , 000 miles ) besides moving round the Sun about 1 , 550 , 000 miles . These

motions and distances , however prodigious as they are , seem nothing compared to those of some of the comets . The distance of the Fixed Stars is yet more vast—they are supposed to be about 400 , 000 times further from us than we are from the Sun , so that a cannon ball would take between four and five millions of years to reach one of them , supposing there was nothing to

hinder it from pursuing its course thither . The tables which Astronomers have formed of the motions of the heavenl y bodies are of great use in navigation . B y means of the eclipses of Jupiter ' s satellites , and by the tables of the Moon ' s motions , we can ascertain the position of a ship at

sea ; for the observation of the Sun's height at mid-day gives the latitude of the place , that is , its distance from the equinoctial or equator , and these tables , with the observations of the satellites , or moonsgive the distance east anel

, west of the observatory for which the tables are calculated—called the longitude of the place : consequently , the mariner can thus tell nearly in what part of the ocean he is , how far he has sailed from his port of departure , and how far he must

sail , and in what direction , to gain the port of his destination . The advantage of this knowledge is therefore manifest in the common affairs of life ; but it sinks into insignificance compared with the vast extent of those views which the contemplations of the science afford , of numberless worlds filling the immensity of space , and all kept in their places , anel adjusted in

their prodigious motions by the same simple principle , under the guidance of an all-wise and all-powerful Creator . The application of Dynamics to the pressure and motions of fluids , constitutes a Science which receives different appellations according as the fluids are heavy and

liquid like water , or light and invisible like air . In the former case it is called Hydrodynamics , from the Greek words signifying ¦ mater and power , or force ; in the latter Pneumatics , fmm the Greek word signifying breath or air ; and Hydrodynamics is

divided into Hydrostatics , which treats of the weight and pressure of liquids , from the Greek words for balancing of water ; and Hydraulics , which treats of their motion , from the Greek word for certain musical instruments played with water in

pipes . The discoveries to which experiments upon the pressure and motion of fluids , aided by mathematical reasoning , have led , are of the greatest importance , whether we regard their application to practical purposesor their use for explaining the

ap-, pearances in nature , or their singularity as the subjects of scientific contemplation . When it is found that the pressure of water or any other liquid upon the surface that contains it , is not in the least degree proportioned to its bulkbut only to the

, height at which it stands , so that a long small pipe , containing a pound or two of the fluid , will give the pressure of twenty or thirty tons ; nay , of twice or thrice as much , if its length be increased , and its

bore lessened , without the least regard to the quantity of the liquid , we are not only astonished at so extraordinary and unexpected a property of matter , but we straightway perceive one of the great agents employed in the vast operations of nature , in which the most trifling means

are used to work the mightiest effects . We likewise learn to guard against many serious mischiefs in our own works , and to apply safely and usefully a power calculated , according as it is directed , either to produce unbounded devastationor to

, render the most beneficial service . Nor are the discoveries relating to the Air less interesting in themselves , and less applicable to important uses . It is an agent , though invisible , as powerful as AVater , in the operations both of nature