In performing either intranasal or external operations on the frontal sinuses, some means of enlarging the nasofrontal duct is essential. Halle and Ingal have each devised drills for this purpose, but they are somewhat cumbersome and dangerous in the hands of the inexperienced. The nasofrontal rasps devised by Thompson and Sullivan enjoy wide popularity on account of their simplicity. For many years I have used the former pattern, but object to the instrument in that it is a scratching or tearing rather than a cutting instrument and the teeth become easily clogged with bone dust and are easily dulled and cannot be sharpened. The handle is also somewhat small and difficult to hold.
The accompanying illustration shows a rasp that I have devised which seems to me to be an improvement on other rasps in the following ways: 1. The teeth are file-cut and can be kept sharp. 2. The