Proceedings of the Polytechnic Association. 1065 : 



Trere trno, wliilc others were not so. Why will a dead body Lave 

 contraction of the muscles ? That the heart is a pump is accepted ; 

 also that the conibnstion of carbon ])roduces heat; but carbon is not 

 burnt in the lungs, for in that case they would be very liot ; whereas 

 they are quite cool. The action of the heart serves to propel the 

 blood until it reaches the ea[>illarics, where they take up the blood 

 by suction. All pressure is lost when the blood gets to the capilla- 

 ries. The extremities of the arteries have no pressure. The capil- 

 laries lie between the muscular fibres, and they form a communication 

 between the venous and arterial system. The capillaries extend to 

 the very marrow of tlie bones ; no part of the human body is so full 

 of blood as the brain, yet the arteries do not extend there. Th'e 

 capillaries are filled M-ith l)lr>od ; they suck it from the arteries ; these 

 Latter are elastic, and as the blood carries everything with it, so that 

 if lime has been taken from the system, the blood that contains the 

 phosphate of lime will be carried all over the body until reaching 

 t.he place where the phosphate is wanted, and there it is left. It is 

 simply the nervous system that causes the circulation of the blood. 



Safety Boilek Feeder. 

 Mr. Dunbar exhibited Mr. D. L. F. Chase's safety boiler feeder. 

 The principal feature of this machine is a hollow metallic steam- 

 tight chamber, suspended from one end of a bar similar to a scale- 

 beam, and supported upon knife-edge bearings, the chaudjcr being 

 counterpoised hj a suitable weight at the opposite end of the bar. 

 The machine is placed at such a height that the plane of the desered 

 water-level in the boiler shall pass nearly through the middle of the 

 chamber, and the steam and water spaces of the boiler are respect- 

 ively connected by pipes with the top and bottom of the chamber in 

 such a manner that the water must remain constantly at the same 

 level, both in the boiler or chamber. As the waterfalls in the boiler, 

 it also falls in the chamber, and the diminution of weight in the latter 

 causes it to rise, though being overbalanced by the additional weight 

 of water in the chaml)er. Above the balance-boam is the driving 

 shaft, by means of which is put in motion a second shaft, which is 

 furnished, af its outer or free end, with a small pinion revolving 

 between the two parts of a double sectoral rack. This pinion-shaft 

 revolves in a vil)ratory arm or sleeve, supported on center bearings, 

 in such manner that the pinion may be brought into engagement with 

 either the ujjper or lower rack. A pitman connects the vibratory 



