OF CASES OF CLEFT PALATE. 7 



tion to a lofty arch, there is a fissure through 

 which, to some extent at least, it is necessary that 

 the wax should pass. 



There are of course other cases yet more 

 difficult, arising from accident or disease, where, 

 from contractions without or within the mouth, 

 nothing but much patience and ingenuity will 

 triumph ; but as these are exceptional cases, it 

 will be useless to advert to them on the present 

 occasion. 



The necessity of modifying the ordinary form of 

 tray for cases where the vault is high, and the 

 ruga3 strongly developed, was forced on my atten- 

 tion by a case where a plate, which was fitted with 

 great fidelity to the model upon which it had been 

 made, stood off considerably at its inner edge from 

 the mouth. After repeated attempts, I failed to 

 improve upon my first model : thinking the tray 

 might be at fault, I made a longitudinal section 

 of the model, and a similar section of the tray, 

 and then I soon saw sufficient reason for my 

 previous failures. The interval between the inner 

 surface of the impression tray and the roof of the 

 mouth, when the tray was carried as near to the 

 latter as the upper incisores would allow, was so 

 great that it was necessary to employ a large body 

 of wax to even reach the roof. The desirableness 

 of using as small a quantity as possible for the 

 comfort of the patient^ for the convenience of the 

 manipulator, and for the success of the result, is 



