CONTENTS. 



XXI 



meter j Different scales ; 648. Temporary change of 

 a thermometer; Air thermometers; 649. Capacities 

 for heat; Natural zero ; 650. Theory of capacities ; 

 651. Chemical effects; Latent heat; C52. Mr. 

 Davy's experiments; Intimate nature of heat; Theory 

 of caloric; Confutation; 653. Heat a quality; 

 Newton's opinion ; Vibrations ; 654. Mechanical ef- 

 fects of vibrations ; Chemical effects ; Comparison 

 with sound; 655. General inferences ; 656,657. 



Lecture liii. Ou electricity in 

 equilibrium ; 6o8. 



Utility of electrical hypotheses; Division of the 

 subject; 658. Supposed electric fluid; Its attrac- 

 tions and repulsions ; 659. Conductors and noncon- 

 ductors ; 660. Positive and negative electricity ; Lo- 

 cal electricity; Distribution of electricity; 661. 

 Electricity of a sphere; Connected spheres; 662. 

 Difference of hydrostatic and electrical pressure; 

 Attractions and repulsions ; 663. Induced electri- 

 city ; Neutral point ; Effects of attraction and repul- 

 sion; 664. Currents of air; Bodies electrified in dif- 

 ferent degrees; Charge; 665. Discharge; Shock; 

 Coated jar; Battery; Comparison of conducting 

 powers; 666, 667. 



Lecture liv. On electricity in 

 motion ; 668. 



Effects and causes of electrical motions, and elec- 

 trical apparatus; Velocity; 668. Spark; Perfora- 

 tion of a jar; Direction of the motion; 669. Opini- 

 ons respecting positive and negative electricity ; Ef- 

 fects of electricity ; Accumulation ; Simple current ; 

 Electric light ; 670. Heat; Mechanical effects ; 671. 

 Chemical effects; Sensible effects; 672. Excitation 

 of electricity ; Electrics; 673. Vapours; Tourmalin; 

 Galvanic electricity; Chemical chanws; 674. G:»l- 

 vanic combinations ; General laws ; 675. Particular 

 facts; Pile of Volta; 676. Troughs; Animal elec- 

 tricity ; 677. Mr. Davy's discoveries ; Electrical na- 

 ture of chemical attractions ; Theory of the pile ; 678. 

 Efficacy of decomposable substances; 679. Electrical 

 machines ; Teylenan machine ; Electrophorus ; 680. 

 Condenser; 681. Multiplier; Doublers ; Electrical 

 balance; Quadrant electrometer; 682. Gold kaf elec- 

 trometer ; Lane's electrometer ; 683. General obser- 

 Tations; 684. 



Lecture lv. On magnetism; 6SS. 



Resemblance of magnetism and electricity ; Theory ; 



685. Conducting powers ; Magnetical substances ; 



686. Aurora borealis; North and South poles ; At- 

 tractions and repulsions; 687. Polarity; Arrange- 

 ment of filings; Directive force; 688. Terrestrial 

 magnetism; Compass; Dipping needle; Illustra- 

 tion ; 689. Temporary magnetism : Natural magnet ; 

 Magnetic poles of the earth ; 690. Diurnal changes j 

 Variation of the declination; Line of no declination; 

 691. Dip; Artificial magnets; 692. Double touch ; 

 Magnetic paste ; Division of a magnet ; 693. Strik- 

 ing and ringing a magnet ; Hammering brass; Solu- 

 tion in an acid ; 694. Resemblance of polarity to 

 crystallization ; 695. 



Lecture lvi. On climates and 

 winds; 696. 



Meteorology; Division of the subject ; Climates; 

 Meteorological thermometers ; 696. Immediate effects 

 of the sun ; 697. Prevost's calculations ; Variations 

 of temperature ; Slow changes ; 698. Heat of the 

 sea ; Effect of freezing and thawing ; Heat of the at- 

 mosphere ; 699. Sunnner and winter ; Temperatures 

 of different places ; Local variations ; 700. Winds ; 

 Periodical winds ; Trade winds; Had ley ; 701. Hal- 

 ley's theory ; Atmosphere of Jupiter; Greater heat of 

 the northern hemisphere ; 702. Westerly winds ; 

 Local modifications; Monsoons; 703; Land and sea 

 breezes; Hurricanes; Variations of the barometer; 

 704, 705. 



Lecture lvii. On aqueous and 

 igneous meteors ; 7O6. 



Evaporation, and its effects; Theory of Deluc and 

 Dallon; 700. Quantity of water evaporating; Preci-" 

 pitation ; 707. ^Moisture; Mediterranean; Currents 

 at the Straights; Attraction of moisture; 708. B. 

 Provost; Hygrometers; 709. Natural hygrometer; 

 Water contained in air; 710. Visible vapour; Dew; 

 Mists; 711. Ruin; Indications of the barometer; 

 Effects of mountains; 712. Periodical rains; Thun- 

 der and lightning; 713. Atniospheiical electricity; 

 Thunderstorms; 714. Conductors; Sudden conden- 

 sations; 715. Wall rspouts;- Aurora borealis; Earth- 

 quakes and Volcaiius; 716. Volcanic countries; 

 Earthquakes of Calabria; 717. Eruptions of Vesu- 



