556 



ILL USTRA TI VE EXPERIMENTS 



the effect of this upon the arterial and venous ])ressures. »Study tlie further 

 effect of constricting D. 



{(■) Place a finger on A and note the expansion with each contraction of H. 

 Study the same thing on D and on F. 



72. Vowel Sounds by Percussion. 



Place the mouth in the position necessary for the pronunciation of the 

 various vowels and then percuss over the cheek (Fig. 96\ Now shift the 

 point of percussion to a position over the pharynx just behind the angle of 

 the jaw^ and percuss again, Note that the "' cheek notes " rise as one passes 

 from U — — A — E — I, while the '" pharynx notes " rise U — — A and fall to 

 E and I. This demonstrates the double nature of the mouth cavity in 

 producing E and I (Fig. 97). 



73. Prepare a series of bladders filled completely w^ith (a) air, {b) water 

 and (c) some viscous Huid like svrup and (rl) lard. Percuss and pal])ate each. 



74. Demonstration of the Effect of Colour on the Absorption of Radiant 

 Energy (L. Hill). 



Two similar pieces of cotton tape, one white and the other black, are 



Arterial BP 



Veins Splanchnic area 



Helrt 

 H 



Fig. 114. — Schema of the ein-ulatioii. 



suspended so that the end of each dips in a graduated cylinder filled with 

 water. Place first in the shade and measure the amount of water evaporated 

 from each cylinder during a period of 30 minutes. Refill with water to the 

 same level and repeat the experiment in direct sunlight. 



75. The Kata-thermometer. 



The instrument is fully described in Chap. XXXIL Before attem])ting 

 to use it the student should study the description and the theory outlined 

 there. 



Cautions, (i.) The bulb is very fragile, and should be handled carefully. 

 With reasonable use the kata-thermometer should have a life as long as an 

 ordinarv thermometer and longer than a clinical thermometer. 



(ii.) The kata-thermometer should never be put into boiling water and 

 should never be left without attention in warm water. 



Method, (a) See that there is a eontinuous thread of spirit in the stem 

 reaching from bulb to upper reservoir (see text, Chap. XXXIL). Dry the 

 bulb. 



(6) Hang the instrument by a thin cord to a stand (a wooden filter stand 

 answers well) and start a stop-watch when the meniscus reaches the upper 



