A tarred rope is about one -fourth weaker than untarred white rope. Tarred hemp and manilla ropes are of about equal strength. Wire rope of the same strength as new hemp rope will run on the same sized sheaves ; but the greater the diameter of the latter, the longer it will wear. One wire rope will usually outlast three hemp ropes. Running wire rope needs no protection ; standing rig ging should bo kept well painted or tarred. The coefficient of friction of leather belts over wooden drums is 047 of the pressure, and over turned cast-iron pul leys o'2B of the pressure. A mixture of 9 parts phosphate of soda, 6 parts nitrate of ammonia, and 4 parts diluto nitric acid is a freezing compound which will cause a fall in temperature of 71°Fah.
Three fourths of a cubic foot of water evaporated per hour will produce 1 horse power. Cold blast iron is stronger than hot blast. Annealing castiron diminishes its tensile strength.
The safe load in tuns which an iron chain will withstand equals the square of the diameter divided by 0,

OTAGO WITNESS.
Odds and Ends.
October f, 18^6.]

Scientific.
SCIENCE FOR THE PEOPLE.
substance, resist boiling heat for a long time, but may afterwards, in a suitable nutritive liquid, develop to what' are termed bacillus rods, and this probability explains one of the results obtained by Dr. Bastian, from which he inferred the possibility of spontaneous generation. There is scope enough for difference of opinion as to the reliability of the ex planation thus offered. Dr. Bastian promises new revelations bearing on the question, and the discussion will Bhortly be resumed.
The Workshop.
FACTS AND SIMPLE FORMULA FOR MECHANICS, AND EN GINEERS.
WHAT TAKES PLACE IN SWALLOWING.
