1. With the cows and machines tested there was a great range in the duration of milking, the coefficient of correlation between yield and duration of milking being 0·429. 2. With some individual cows the correlation between yield and duration was high, and lines representing the regression of the duration of milking relative to the amount of milk drawn have been constructed. 3. Average composite curves representing the rate of milking at various stages during the complete operation have also been set out for varying yield groups. The main conclusions to be drawn from these curves are: (a) With some cows the rate of flow was noticeably checked about –1 min. after milking commenced. This check was of temporary duration. (b) Maximum rate of flow in all yield groups was reached about 2 min. after milking commenced. (c) A very much more rapid rate of flow was recorded with high yields than with low yields. (d) The decrease in rate of flow near the end of milking was rapid, especially with high yields.