Serghis MorguUs 149 



which it is interlocked with the f rame, e, f, g, h. When the plate, ^2, 

 is attracted, the yoke, So, moving upwards opens the catch, m, held 

 down firmly by a spring. This causes the frame to shift to the left, 

 as already explained, allowing an increased delivery of gas. This 

 side movement of the frame brings bar / close to the cross piece of 

 the yoke, ^^ of the opposite electromagnet. When this magnet is 

 activated and attracted to the iron axis, it pulls strongly on the 

 frame, shifting it back to the right and the catch, m, again clutches 

 the bar, e^ preventing the frame from striking back. 



We have yet to consider the contact-makers, which, according to 

 circumstances, bring into play either one or the other electromagnet. 

 In the respiration apparatus I utilize, for this purpose, the Spirometer, 

 which is a Hght aluminum bell floating in a water- jacket formed by 

 two concentric metal pipes. The bell, being exactly counterpoised, 

 responds very quickly to changes in the volume of the air, dropping 

 when the volume is diminished by the using up of oxygen, for 

 instance, and rising when the volume increases. A small metal rod 

 is soldered to the edge of the top of the bell, as will be seen from 

 Plate 2, which passes through a narrow slit in the frame upon which 

 the Spirometer bell (6) is suspended. Two hard rubber blocks are 

 attached to the frame: one (3) very near the base is fixed perma- 

 nently, while the other (4) can be moved the entire length of the 

 frame by means of a continuous screw (5) . In this way any distance 

 may be set between these two blocks. On the top of each block 

 there are two little holes filled with mercury which is in contact with 

 binding posts for the electric wires on either side of the block. The 

 contact is effected by a small metal fork (8) with platinum teeth, 

 Avhich moves on a fulcrum set in the middle of the block. One end 

 of the fork is made sufficiently heavy so that the part bearing the 

 platinum points is always raised. When the Spirometer bell, moving 

 downwards, reaches a very low level, it presses with its hook-like 

 projection upon the fork and causes its platinum points to dip into 

 the mercury cups, thus closing the contact and sending the current 

 through the left electromagnet. This releases the catch, m, and the 

 tube is decompressed. The oxygen flows, now, at a maximum rate 

 and the Spirometer bell fills up rapidly, rising to the level at which 

 the moveable contact-block has been set. As soon as it reaches this 



