354 
Utilisation of Waste Substances and 
of 57s. 8(/. over the first 8 years (including the period of the 
Crimean War) to 495. over the last 3 years. 
The annual value of the home produce available for consump- 
tion has declined from an average of nearly 38,000,000Z. over 
the first 8 years, to less than 25,000,000/. over the last 3 years. 
The annual value of the imported wheat has increased from an 
average of little more than 13,000,000/. over the first 8 years, to 
more than 33,000,000/. over the last 3 years. 
The annual value of the total wheat estimated to be consumed 
has ranged from under 40,000,000/. to more than 71,000,000/. ; 
and it has increased from an average of about 51,500,000?. 
over the first 8 years, to more than 58,000,000/. over the last 
3 years. 
The average annual cost of wheat per head has somewhat 
reduced in the later periods ; and it has been 36s. 2</. over the 
27 years. 
Over the whole period of 27 years, 40'4 per cent, of the wheat 
consumed has been derived from imports ; and the amount sup- 
plied from foreign sources has increased from an average of 
26"5 per cent, of the total over the first 8 years, to 57*4 per cent, 
of the total consumed over the last three years, of the 27. 
XXI. — Utilisation of Waste Substances and Economical Manage- 
ment of Materials, Machines, and Appliances on the Farm. 
By Robert Scott Burn, Consulting Farm Architect and 
Engineer, 
Characteristics of the Subject. — A glance at the title of this 
paper will show the comprehensive character of the general 
subject with which it proposes to deal. That, however, em- 
braces a much wider range of topics than even the title fore- 
shadows, as it is proper to observe that this paper was drawn up 
more with the view to make it suggestive, than that its tenor 
should be rigidly precise and definite. 
In point of fact it is difficult, if indeed it be not here impos- 
sible, to limit the topics which the subject embraces. For that 
defined, as it may with rigid accuracy be so defined, as the 
" science of economy," takes within its range almost everything 
material. To those who at first sight may object to this impor- 
tant status here claimed for it, perhaps the following, by an 
able authority, may be suggestive as bearing thereon. Referring 
to the operations of practical chemistry, in the various classes 
of technical work in which the principles of that science are 
