The art of procuring pleasant dreams Page take a sea voyage. 119 On the effect of air on the barometer, and the benefits Tendency of rivers to the sea. Effects of the sun's rays on eloths of different colours 155 On the magnetism and theory of the earth 160 Queries and conjectures relating to magnetism and the theory of the earth. 165 On the nature of sea coal 169 Effect of vegetation on noxious air 170 Observations on the prevailing doctrines of life and 171 death END OF VOL. L. T. Davison, Printer, Whitefriars. ESSAYS AND LETTERS ON COMMERCIAL AND POLITICAL SUBJECTS. OBSERVATIONS CONCERNING THE INCREASE OF MANKIND, PEOPLING OF COUNTRIES, &c. Written in Pennsylvania, 1751. 1. TABLES of the proportion of marriages to births, of deaths to births, of marriages to the number of inhabitants, &c. formed on observations made upor the bills of mortality, christenings, &c. of populous cities, will not suit countries; nor will tables, formed on observations made on full settled old countries, as Europe, suit new countries, as America. 2. For people increase in proportion to the number of marriages, and that is greater, in proportion to the ease and convenience of supporting a family. When families can be easily supported, more persons marry, and earlier in life. 3. In cities, where all trades, occupations, and offices are full, many delay marrying till they can see how to bear the charges of a family; which charges are greater in cities, as luxury is more common: many live single during life, and continue servants to families, journeymen to trades, &c. |