Page:Popular Science Monthly Volume 47.djvu/419

Rh of the star Vega. We have reason to believe this to be the first successful experiment ever made either in this country or abroad." Some daguerreotypes of the moon and certain stars were exhibited in the World's Fair of the following year at London, and received a council medal.

The inventive skill which won success for Bond as an artisan appears in certain astronomical appliances and methods devised by him. The great telescope is poised thirteen feet above the floor of the observatory's dome. It has a vertical sweep of more than ninety degrees, and can, of course, make a complete revolution about its axis of support. An observer would evidently have to be something of an acrobat to use it successfully, unless a suitable chair could be obtained. There was none in the world that filled all the requirements, so Prof. Bond invented and made one. It is in use unchanged to this day, and by means of its ingeniously combined wheels, cogs, and pulleys the observer can quickly and easily place himself anywhere along the vertical quarter-circle and horizontal full-circle traversed by the eyepiece of the telescope.

Certain experiments for determining differences of longitude by the aid of the telegraph were undertaken by the Coast Survey in 1848, Prof. Bond being one of the special assistants whose services were secured for this work. While engaged in these experiments the idea occurred to him, as it had to one or more others, of using an automatic circuit interrupter in place of human nerves and muscles as the connecting link between the astronomical clock and the electric wire. Fear of injuring the clock had prevented the use of such a device, but Prof. Bond obtained authority to have a clock made especially for this work, at the expense of the survey. This was done, and the device was found to operate perfectly and without injury to the clock. "But another and far more serious difficulty presented itself," says Prof. Bond, referring to this matter in one of his reports, "in the accurate registry of the beats of the clock after being transmitted by the galvanic circuit; and it was at this point that further progress in the application of this method to astronomical observing was arrested." Attempts to overcome this difficulty were made by various inventors in the course of the next two years, but nothing satisfactory came of it before April 12, 1850, when Bond submitted to the Coast Survey an apparatus invented by him and his sons George P. and Richard F. Bond. It was named at first, from one of its peculiar parts, the "spring governor," but the more comprehensive title of "chronograph" was applied to it later. The apparatus was at once adopted for use by the survey. It was taken by Mr. G. P. Bond on his tour to Europe of the next year and exhibited before the Royal Astronomical Society of England and the