Recording Thermometers for Clinical Work. 551 



the mouth closed for three minutes previous to the insertion 

 of the thermometer. Curve No. (3), which is practically a 

 reproduction of the record already given in fig. 3, represents 

 the result of keeping the mouth closed for ten minutes 

 previously. There is a further improvement with this 

 thermometer after closure for fifteen minutes, but unless the 

 mass of the thermometer is very small, or the thermometer 

 itself is previously warmed, little advantage is gained by 

 keeping the mouth closed more than ten minutes, because 

 in any case the mouth takes some time to recover from the 

 cooling effect of inserting the thermometer. In all the 

 records given in figs. 3 and 4, the thermometer was inserted 

 cold, being taken direct from a water-bath at 15° C. The 

 difference between the records in fig. 4 is due almost entirely 

 to an actual difference in the temperature of the mouth at 

 starting. The difference between the quartz and platinum 

 tube thermometers in fig. 3 is due chiefly to the greater 

 cooling effect of the quartz tube, owing to its greater mass 

 in proportion to its surface. 



(2) For records of long duration, the best results are 

 undoubtedly to be obtained by insertion in the rectum. The 

 thermometer bulb should be of small dimensions and the 

 leading wires should be enclosed in a flexible but inextensible 

 tube of small diameter, such that it can be attached to the 

 bulb in a perfectly secure and water-tight manner. Such a 

 thermometer may be made in a variety of ways. The 

 following is a description of a method of construction which 

 I have found very satisfactory. The fine wire forming the 

 bulb is wound on a thin celluloid tube 5 mm. in diameter, 

 and is protected by another thin celluloid tube which closely 

 fits the first. One end of the protecting tube is closed by a 

 small celluloid stopper, the other is cemented with celluloid 

 cement to the cut end of a Porges catheter 5 mm. in external 

 diameter, and 32 cm. long, through which the flexible 

 thermometer and compensator leads are passed. This type 

 of catheter has a smooth surface, and is very flexible, but 

 practically inextensible, thus protecting the leading wires 

 and joints from possible strain. It also makes a very good 

 joint with the celluloid tube protecting the bulb. I have 

 tried rubber tubes and metal bulbs, but these appear to be in 

 every respect less suitable. A rubber stopper fixed on the 

 catheter at a distance of 3 to 5 cm. from the near end of 

 the bulb, is a convenient method of limiting the depth of 

 insertion. The thermometer is smeared with vaseline before 

 insertion. This prevents irritation, and does not appear to 

 have any injurious effect on the celluloid or catheter. 



