62 THE POPULAR SCIENCE MONTHLY, 



We have determined the average length of life of the adepts of the 

 science of the sky who died before 1780 and of those who have died 

 since that year. We have obtained sixty-three years and six months 

 for the former, and sixty-four years and eleven months for the latter. 

 The advantage in favor of these is not to be despised. 



Taking a hundred individuals in each of these categories, there 

 died at different ages : 



Before 1870. After 1870. 



Before seventy years of age 62 57 



Between seventy and seventy-nine 23 28 



Between eighty and eighty-nine 12 13 



Between ninety and ninety-nine 2 2 



Over a hundred , 1 



The conclusion at which we arrive has already probably occurred 

 to more than one reader. Become an astronomer, if you wish to live 

 long. We will add, whoever follows this counsel will not only see 

 the limits of his life far removed, but he will also find in the study and 

 contemplation of the heavenly bodies a satisfaction more durable than 

 any earthly pleasures. — Translated for the Popular Scietice Monthly 

 from del et Terre. 



♦-«-♦ 



THE CHEMISTRY OF COOKEEY. 



By W. MATTIEU WILLIAMS. 



xxvni. 



I NOW proceed to examine the chemical changes which occur in 

 the course of the cookery of vegetable substances used for food. 

 My readers will remember that I referred to Haller's statement, 

 ^^ Dimidium corporis hicmani gluten est,^^ which applies to animals 

 generally, viz., that half of their substance is gelatine, or that which 

 by cookery becomes gelatine. This abundance depends upon the fact 

 that the walls of the cells and the framework of the tissues are com- 

 posed of this material. 



In the vegetable structure we encounter a close analogy to this. 

 Cellular structure is still more clearly defined than in the animal, as 

 may be easily seen with the help of a very moderate microscopic power. 

 Pluck one of the fibrils that you see shooting down into the water of 

 the hyacinth-glasses just at this season, or, failing one of these, any 

 other succulent rootlet. Crush it between two pieces of glass, and 

 examine. At the end there is a loose, spongy mass of round cells ; these 

 merge into oblong rectangular cells surrounding a central axis of spiral 

 tube or tubes, or greatly elongated cell-structure. Take a thin slice 

 of stem, or leaf, or flower, or bark, or pith, examine in like manner, 

 and cellular structure of some kind will display itself, clearly demon- 



