PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 421 



has long been prepared by the Indians of Yucatan, using very primitive 

 apparatus, enabling one man to prepare about four or five pounds per day 

 of fiber. Machinery has lately been introduced, which was explained by 

 Ml-. S., for preparing the fiber. He alleged that one machine attended by 

 two men or boys in ten hours would produce 500 pounds, better cleaned 

 than by the primitive process. He believed it was a fiber entitled to much 

 attention. Some of the waste, a short fiber, was now in the hands of Mr. 

 John Priestly, an extensive manufacturer of this city, and paper from it 

 would be exhibited at a future meeting of this Association. Some fifteen 

 tons of this waste had been recently brought to this port, but for what pur- 

 pose or price, he Mr. S. had not learned. He believed the machine de- 

 scribed, which was the invention of Mr. E. I. Patrulla of Merida, an exten- 

 sive cultivator of this material, was a curiosit}'^ as a very marked example 

 in which extreme simplicity and gi'eat economy of production had been 

 reached through experiments with more complex and inferior apparatus. 

 The machine now is little more than a drum with teeth, running in a tight case. 



The Chairman. — I have the pleasure of introducing to the meeting Mr. 

 Hyslop, who will make some remarks on ventilation, and illustrate the 

 action of air currents in rooms; and conclude by exhibiting Mr. McKinnell's 

 ventilating apparatus, which was several years since patented in England, 

 and is extensively used there. 



Mr.' Hyslop after some remarks upon the importance of perfect ventila- 

 tion, proceeded to give a practical illustration of this subject. 



He showed that an opening in the top of a room, or a pipe of any kind 

 carried from the ceiling to the outside and above the roof, would not alone 

 remove foul air; he placed three lighted candles under a glass shade which 

 had a large opening through the top of it; the oxygen of the air was soon 

 so far exhausted that the lights were extinguished; he next repeated the 

 experiment, placing an open tube upon the opening, such as are commonly 

 used for carrying off foul air from public buildings, and the lights were 

 extinguished as before; he then relighted the three candles and placed them 

 under the glass shade and about three inches apart, in the form of a tri- 

 angle; he fixed an 04)en tube in the opening on the top of the shade, and 

 raised the lower edge of the shade on one side, by putting the point of a 

 pencil under it, opposite the center light; this admitted a free current of 

 air, which came in at the bottom and went out thr jugh the tube at the top; 

 the effect of this was that the light opposite the opening made bj' the pen- 

 cil was kept burning brightly, but was agitated by the draught, whilst the 

 lights on each side of it were extinguished by the deficiency of oxygen in 

 their locality; he argued from this experiment that the lower part of a room 

 was the wrong point at which to admit fresh air, as it passed through the 

 room without diffusing itself, causing inconvenient draughts where it went, 

 and leaving some parts unvisited. 



He then covered the opening in the top of the shade and placed three 

 lights in it at different levels; one near the top, one at the bottom, and one 

 about midwaj' between the other two; no change of air was allowed, and 

 as the carbonic acid began to accumulate the lights were extinguished; 

 the highest first and the lowest last. Mr. Hyslop showed by this that car- 

 bonic acid ascended to the ceiling, and accumulated downward from that 



