979 Royal Society^ 



their mean values: whence it appears, in respect to the annual 

 temperature, for example, that in any particular year there is an equal 

 probability that its mean temperature will fall within the limits of 

 43°*8 and 44°*6, as that it will exceed those limits on either side. 



Finally, the author has shown the " Thermic Anomaly" (as it has 

 been recently termed) of the monthly and annual temperatures at 

 Toronto by comparison with the normal temperatures computed by 

 Dove (Verbreitung der Warme, 1852), for the parallel of 43° 40' N. 

 from 36 equidistant points on the parallel; from which comparison 

 it appears that after allowance has been made for the elevation above 

 the sea (342 feet), every month of the year is colder than the normal 

 temperature of the same month in the same parallel ; that the thermic 

 anomaly reaches its extreme in February, when it exceeds 10° of 

 Fahrenheit ; and that on the average of the whole year it is little less 

 than 6°. 



Feb. 17. — A paper was read, entitled *' On the Muscles which 

 open the Eustachian Tube." By Joseph Toynbee, M.D., F.R.S. 



The author commences by alluding to the opinion generally held 

 by anatomists, viz. that the guttural orifice of the Eustachian tube 

 is always open, and that the air in the tympanum is constantly con- 

 tinuous with that in the cavity of the fauces. An examination of 

 the guttural orifice of the tube in man and other animals has led the 

 author to conclude, that, except during muscular action, this orifice 

 is always closed, and that the tympanum forms a cavity distinct and 

 isolated from the outer air. The muscles which open the Eustachian 

 tube in man are the tensor and levator palati, and it is by their ac- 

 tion during the process of deglutition that the tubes are ordinarily 

 opened. That the act of swallowing is the means whereby the Eu- 

 stachian tubes are opened, is shown by some experiments of which 

 the following may be cited. If the mouth and nose be closed during 

 the act of swallowing the saliva, a sensation of fulness or distension 

 is produced in the ears ; this sensation arises from the air, which is 

 slightly compressed in the fauces, passing into and distending the 

 tympanic cavities : upon removing the hand from the nose, it will be 

 observed thatthis feeling of pressure in the ears does not disappear, 

 but it remains until the act of deglutition is again performed while 

 the nose is not closed. In this experiment the Eustachian tubes 

 were opened during each act of deglutition ; during the first act, 

 while they were open, air was forced into the cavity of the tympanum 

 by the contraction of the muscles of the fauces and pharynx, and the 

 guttural orifices of the tubes remained closed until the second act of 

 swallowing, which opened the tubes and allowed the air to escape. 

 That the act of deglutition opens the Eustachian tubes, was inferred 

 also from the custom usually adopted of swallowing while the de- 

 scent in a diving-bell is performed ; by this act the condensed air is 

 allowed to enter the tympanum, and the sensation of pain and pres- 

 sure in the ears is removed or entirely avoided. 



The author gives an account of the Eustachian tube and its 

 muscles in Mammalia, Birds and Reptiles. In some mammalia the 

 muscles opening the tubes appertain, as in man, to the palate, in 

 others this function is performed by the superior constrictor muscles 



