Shaffer, Douglas Howerth, <br/><br/>
A survey history of the American spring driven clock, 1840-1860 / 
D.H. Shaffer. 
 - 34 pages ;  24 cm 
<br/><br/> Cover: "A 'Living Monograph' presented at the NAWCC Thirtieth Anniversary Convention, Pittsburgh, Pennsylvania, June, 1973". 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Clocks and watches--History--United States--1840-1860.
<br/><br/><label>Subjects--Index Terms: </label>catalog NAWCC National Pittsburg Clock (general) History Exhibition