Having for a number of years been constantly moving about, in situations where I could not convey large astronomical instruments, I have repeatedly tried to what extent of accuracy and consistency I could arrive with the smaller ones. The results have convinced me, that a great deal of accuracy may in that way be obtained; and that the sextant is an instrument, which, if perfectly understood, would be in higher estimation, and more general use, than it is at present. The observations I am about to submit, were made with a ten inch sextant of Troughton's, divided on platina to 10″, (No 1200).