"This book is written to show that the value of oil to a user of power - the price per gallon that he can afford to pay - depends on the answers to these questions: (1) how easy does it make his machineryy go? (2) how much power does it save? (3) how much it this savable power worth in his particular works?..." Воспроизведено в оригинальной авторской орфографии издания 1899 года (издательство "Vacuum Oil Company").