CONTENTS OF VOLUME II. 



9 



THE LATITUDES AND LONGITUDES page 559 



Definition of the Equator and Poles.— Northern and southern Hemispheres.— Latitude of a Place. — 

 Parallel of Latitude.— Meridian of a Place. — Longitude of a Place.— Standard Meridian.— Meth- 

 ods of determining Latitude and Longitude various. — To find the Latitude. — Methods applicable 

 in Observatories. — At Sea. — Hadley's Sextant. — To determine the Longitude. — How to find the 

 Time of Day at Land. — At Sea. — Use of Chronometers. — Lunar Method of finding the Longi- 

 tude.— Apparatus provided at Greenwich for giving the exact Time to Ships leaving the Port of 

 London.— Method of determining Longitude by Moon-culminating Stars. 



THEORY OF COLORS , 573 



Refraction of a Ray of Light. — At plane Surfaces.— By a Prism.— The Prismatic Spectrum.— The 

 Decomposition of Light. — Newton's Discoveries. — Colors of the Spectrum. — Brewster's Discovery 

 of three Colors. — How three Colors can produce the Spectrum.— Colors of natural Bodies.— How 

 they are produced. 



THE VISIBLE STARS 583 



What occupies the Space beyond the Limits of the Solar System. — Wide Vacuity between this 

 System and the Stars. — Indications of this observable in the Motions of the Planets. — Indications 

 in the Motions of the Comets. — The immence Distance of the Stars proved by the Earth's annual 

 Motion. — Observations made at Greenwich. — Bessel's Discovery of the Parallax. — The conse- 

 quent Distance of the Stars. — Illustrations of the Magnitude of this Distance. — The different 

 Orders and Magnitudes of the Stars.— How accounted for.— Why those of the lowest Magnitude 

 are most numerous. — The real Magnitude of the Stars. — The Telescope unable to magnify 

 them. — Dr. Wollaston's Investigations of the comparative Brightness and Magnitude of the Stars 

 in relation to the Sun.— Their stupendous Magnitude. — Application of this to the Dog-Star. 



WATERSPOUTS AND WHIRLWINDS 597 



Character and Effects of Water-Spouts. — Difference between Water and Land-Spouts. — Land- 

 Spout at Montpellier. — Land-Spout at Esclades. — Columns of Sand on the Steppes of South 

 America. — Meteor at Carcassonne. — Meteor at Dreux and Mantes. — Land-Spout at Ossonval. — 

 Meteor witnessed and described by M. Peltier. — Conversion of a Storm into a Land-Spout. — 

 M. Peltier's Tables of Water-Spouts and Land-Spouts. — Analysis of the above Tables. — Water- 

 Spouts seen by Captain Beechy. — Experimental Illustration of the Phenomena. — Illustration 

 of the gyratory Motion of Water-Spouts. — M. Peltier's Deductions concerning Water-Spouts. — 

 Action of charged Clouds on light Bodies. — Noise attending Water and Land-Spouts. — Trans- 

 ition from direct to gyratory Motion. — Effect of Induction on watery Surfaces. — Disappearance 

 of Pools, &c. 





