back and hanging down- the arch is the sounder. tongue, and just back of the ward two strong brackets for the support of the main center of the magnet is a post provided with the con- lenses; and to improve photographic pictures by the gear. The crank is variable, and the sliding block is tact… … OBJECT LENS FOR TELESCOPES AND CAMERAS, BELT’S TELEGRAPH KEY AND SOUNDER. Ce Better Pyrometers Needed. produce a stereoscopic effect in the picture. The lens the binding posts for the finger key, which are con- At a recent general meeting of the German Union of is of compound or double form, each…
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![An illustration from Essai de physique, par Mr. Pierre van Musschenbroek ... avec une description de nouvelles sortes de machines pneumatiques, et un recueil d'expériences par Mr. J. v[an] M[usschenbroek] Traduit du hollandois par Mr. Pierre Massuet .. (1751)](https://img.insideoutlibrary.com/img/200/ia-essaidephysiquep02muss-165-43.webp)
