374 JOURNAL OF THE PLYMOUTH INSTITUTION. 
THE ULTIMATE LIMITS OF FOOD PRODUCTION. 
ABSTRACT OF MR. ROBERT SMITH’S PAPER. 
(Read February 28th, 1878.) 
For the production of food certain materials are requisite. 
Although some of these materials, such as water, iron, &c., are 
so abundant that we need scarcely consider them as effectually 
limiting the production, others are strictly limited; such are the 
phosphates and nitrogenized compounds. After touching on the 
manufacture of nitrogen compounds from the atmosphere, the 
lecturer pointed out that the economy of exhausted food con- 
stituents is highly desirable. Other conditions are necessary 
besides an unlimited supply of ponderable materials; viz., a 
proportionate supply of force or energy. Source of this supply in 
vegetables. Remarks on the land question, and speculations as to 
its future, concluded the lecture. 

THE SPIRIT OF MODERN ENQUIRY. 
ABSTRACT OF MR. W. HARVEY’S PAPER. 
(Read March 7th, 1878.) 
Tue importance of clear ideas of investigating nature was strongly 
insisted on. The exactness and thoroughness of physics may now 
be applied to mental and moral science. The causes of medieval 
failure may be instructive even now. The middle ages were 
stationary in science, because they bowed to authority, and failed 
in experiment. The metaphysicians failed to establish philosophy 
on a firm basis. Mental philosophy must be based upon observa- 
tion, internal and external. Phrenology, an empirical science, 
was traced in its effect in mental science. Experiment and 
observation in physics is now the recognized method. The same 
principles apply equally to history, to sociology, and to all enquiry. 
