iv CONTENTS. 



PACK 



effects of light and shade. 48. Uses of the Lieberkuhn. 49. 

 Effects of diffraction and interference. 50. Use of daylight. 

 51. Artificial light. 52. Protection of the eye. 53. Pritchard's 

 analysis of the effects of illumination 33 



CHAP. IV. Pritchard's analysis* of the effects of illumination (con- 

 tinued). MEASUREMENT OF OBJECTS : 54. Measurement distinct 

 from magnifying power. 55. Measurement by comparison with 

 a known object. 56. Micrometric scales. 57. Thin glass 

 plates. 58. Micrometers. 59. Le Baillifs micrometer. 60. 

 Jackson's micrometer. 61. Measurement by the camera lucida. 

 62. Goniometers. MAGNIFYING POWER : 63. This term much 

 misunderstood. 64. Its exact meaning. 65. Least distance of 

 distinct vision. <56. Visual estimate of angular magnitude. 

 67. Method of determining magnifying power by the camera 

 lucida. 68. Dimensions of the least object which a given power 

 can render -visible 49 



CHAP. V. MIOROPOLARISCOPE : 69. Polarisation. 70. Condition of 

 a polarised ray. 71. Polarisation by double refracting crystals. 

 72. Their effect upon rays of light. 73. The micropolariscope. 

 THE MOUNTING OF MICROSCOPES: 74. Conditions of efficient mount- 

 ing. 75. Frauenhoffer's mounting. 76. Methods of varying the 

 direction of the body. CHEVALIER'S UNIVERSAL MICROSCOPE : 77. 

 Mounting of this instrument. 78. Method of rendering it verti- 

 cal. 79. Method of adapting it to the view of chemical pheno- 

 mena. 80. Method of condensing the light upon the object. 

 Ross's IMPROVED MICROSCOPE : 81. Useful labours of Mr. Ross. 

 82. Details of his improved microscope . . . .65 



CHAP. VI. 83. His object-glasses. MESSRS. SMITH AND BECK'S 

 MICROSCOPE : 84. Their largest and most efficient instrument. 

 85. Their smaller microscope. 86. Their object-glasses. 87. 

 Varley's microscope. M. NACHET'S MICROSCOPE : 88. Their 

 adaptation to medical and chemical purposes. 89. Multiple 

 microscopes. 90. Double microscope. 91. Binocular micro- 

 scope. 92. Triple and quadruple microscopes . . . .81 



THE WHITE ANTS ; THEIR MANNERS AND HABITS. 



CHAP. I. 1. Their classification. 2. Their mischievous habits. 

 3. The constitution of their societies. 4. Chiefly confined to the 

 tropics. 5. Figures of the king and queen. 6. Of the workers 

 and soldiers. 7. Treatment of the king and queen. 8. Habits 

 of the workers. 9. Of the soldiers. 10. The nymphs. 11. 

 Physiological characters. 12. First establishment of a colony. 

 13. Their use as food and medicine. 14. The election of 

 the king and queen. 15. Their subsequent treatment. 16. 

 The impregnation of the queen. 17. Figure of the pregnant 

 queen. 18. Her vast fertility. 19. Care bestowed upou her 

 eggs by the workers. 20. The royal body-guard. 21. The 

 habitation of the colony. 22. Process of its construction. 23. 



