EXPLANATION OF THE CONSTRUCTION AND USE.

...is made more firmly: And in addition, there are three oblong iron supports extending from its center all the way to the end of the foot, two of which are indicated by the letters I and H. The third is hidden on the rear side; these can also be attached and removed by their own screws. Furthermore, there are four steel screws which support the entire instrument, three of which are marked with the letters H. The fourth is not visible from the other side. These provide convenience so that the instrument may be correctly and firmly directed, as they are turned upon certain small metal plates placed beneath them—lest they press unevenly into the floor below due to their weight and sharpness—until the observer has found the instrument to be aligned with the plane of a particular vertical circle an imaginary circle passing through the zenith and the horizon, determined by an attached plumb line.

Its use, when managed in this way, is for measuring all Altitudes the height of an object above the horizon, both of the luminaries the Sun and Moon and of the other wandering stars the planets and fixed stars, exactly within a third or fourth part of a minute roughly 15 to 20 seconds of arc; provided they do not exceed a sixth part of the sky 60 degrees, the span of a sextant. Indeed, if the quadrant is fixed differently here—namely, so that the line A C looks toward the Zenith the point directly overhead—the remaining part of the sky can be measured. However, only Altitudes are detected in this way, and not simultaneously the AzimuthsThe horizontal direction or bearing of a celestial body.. Such a sextant is very well-suited not only for Altitudes but also for investigating the distances between stars with precision.

Nor does it suggest any difficulty or uncertainty in this practice original Latin: "pragmateia," referring to the systematic work of observation, since it consists of few parts, and those (as I said) are firmly joined together; lest anything in it be pulled out of its proper alignment during observation. It also offers one particular benefit (which we mentioned before): it can be transported to other places without difficulty and without damage or inconvenience. This is something that ought to be provided for in certain instruments, as far as possible, so that we are not slaves to particular places. For it is necessary for an Astronomer, rather than one devoted to