DIY History | Transcribe | Scholarship at Iowa | Theory of least squares applied to the problems arising in our observatory by Arthur George Smith, 1895 | Theory of Least Squares Applied to the Problems Arising in our Observatory by Arthur George Smith, 1895, Page 78

[page]73[/page]
The equatorial thus reduced gives, when expressed in arc, the value of the number of revolutions of the micrometer screw at which the screw was set, plus a constant error of the micrometer known as the [underlined]index error[/underlined]. It is not possible for the eye, in general, to determine without some error when two objects such as two wires are in exact and perfect coincidence. Hence the micrometer instead of being so constructed that the fixed and movable parallel wires may be made to coincide, the movable wire can only be brought into close proximity with the fixed. The amount

[page]73[/page]
The equatorial thus reduced gives, when expressed in arc, the value of the number of revolutions of the micrometer screw at which the screw was set, plus a constant error of the micrometer known as the [underlined]index error[/underlined]. It is not possible for the eye, in general, to determine without some error when two objects such as two wires are in exact and perfect coincidence. Hence the micrometer instead of being so constructed that the fixed and movable parallel wires may be made to coincide, the movable wire can only be brought into close proximity with the fixed. The amount