One by one, as they became old enough, they were drafted into the service of counting seconds by the chronometer, during the observations.
Some of them took an interest in the thing itself, and others considered it rather stupid work, but they all drank in so much of this atmosphere, that if any one had asked a little child in this family, "Who was the greatest man that ever lived ?" the answer would have come promptly, "Herschel." Maria very early learned the use of the sextant.

The chronometers of all the whale ships were brought to Mr.Mitchell, on their return from a voyage, to be "rated," as it was called.

For this purpose he used the sextant, and the observations were made in the little back yard of the Vestal-street home.
There was also a clumsy reflecting telescope made on the Herschelian plan, but of very great simplicity, which was put up on fine nights in the same back yard, when the neighbors used to flock in to look at the moon.

Afterwards Mr.Mitchell bought a small Dolland telescope, which thereafter, as long as she lived, his daughter used for "sweeping" purposes.
After their removal to the bank building there were added to these an "altitude and azimuth circle," loaned to Mr.Mitchell by West Point Academy, and two transit instruments.

A little observatory for the use of the first was placed on the roof of the bank building, and two small buildings were erected in the yard for the transits.