X. SPECIAL COLLECTIONS. 809 



its movements on a revolving cylinder, and at the same time presses on a 

 tympanum, which communicates through an india-rubber tube with a Marey's 

 cardiograph. If the cardiograph is made to register on the cylinder 

 immediately under the spring, both curves may be compared. When the 

 disc rotates slowly both curves are alike ; with increasing velocity the 

 difference augments. (Compare the curves ; some are an imitation of 

 physiological curves.) 



3956. Brondgeest's Pansphygmograph. To register the 

 movements of respiration, the beating of the heart, and the pulse 

 of different arteries. Dr. Brondgcest, Utrecht. 



The little box contains : 



1 . Cylinder, with internal spring, to be wound up by the hand. 



2. Two Marey's sphygmographs to register on the blackened cylinder 



simultaneously respiration and pulse curve. 



3. Little box with pens, to register, if desired, with ink on white paper. 



4. A large tympanum, to register respiration, to be fastened with a tape 



round the chest or stomach. 



5. Tympanum, with wooden plate and pin enclosed in a hoop, to be applied 



on the heart or on an artery. 



6. Glazed papers for the cylinder. 



7. Curves of respiration and pulse obtained simultaneously with the 



instrument. 



3957. Scheme of the Circulation of the Blood (for instruc- 

 tion). Prof. Danders, Utrecht. 



An elastic bag with valves sucks water up from a vessel. By repeatedly 

 pressing on the bag (with a lever) undulations are determined either in a glass 

 or into an elastic tube, producing an interrupted or a continuous flowing out. 

 On a long bent elastic tube the simultaneous existence of streaming and pro- 

 pagation of waves is further shown, and by means of two little springs on 

 adjoining places of the tube the velocity of propagation of the wave is demon- 

 strated, and if desired registered (also with different pressures indicated by a 

 manometer). The tube at the same time offers an opportunity for ausculta- 

 tion before and behind a dilatation. (Compare Bonders, Physiologie des 

 Menschen. Leipzig, B. I, p. 78. Zweite Ausgabe, 1859.) 



3957a. Prof. Rutherford's Model of the Circulation for 



explaining the Blood Pressure and the Pulse. 



Prof. Rutherford, Edinburgh. 



Model of the circulation for .explaining the blood pressure and the pulse. 

 The tubes are filled with water. The heart is represented by an elastic pump. 

 The apparatus is fully described in the Journal of Anatomy and Physiology, 

 Vol. VI., p. 249.' 



3958. Scheme of the relations of Pressure in the mechanism 

 of Respiration. Prof. Donders, Utrecht. 



A glass cylinder (thorax), closed underneath by an elastic membrane (dia- 

 phragm), at the top by a stopper with three openings: 1st, for a tube (trachea) 

 with india-rubber bladder (lungs) ; 2nd, for a manometer, communicating with 

 the space in the cylinder ; 3rd, for a tube to regulate the pressure of the air in 

 the thorax. This pressure is made negative, as it is in reality ; which causes 

 the air to enter the india-rubber bladder, and the diaphragm to become 

 convex upwards. By pulling the diaphragm down (inspiration) the pressure 

 in the thorax decreases and the lung is more distended ; the resistance of the 

 lung is the negative pressure indicated by the manometer, Instead of an india- 



