[34] A few of these instruments, such as the Marvin barograph, survived for some time because of their superior accuracy. Even as museum pieces, only a few exist today. U.S. GOVERNMENT PRINTING OFFICE, 1961. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington 25, D.C. - Price 25 cents Transcriber's Note: Minor errors in punctuation have been corrected without note. The following typographical errors in the original have been corrected: P. 110: 'a panopoly of gadgetry': corrected to panoply P. 113, caption to Figure 13: 'Feuss': corrected to Fuess Footnote 28: 'Gewerbeaustellung': corrected to Gewerbeausstellung Footnote 28: 'Physikalisches Worterbuch': corrected to Wörterbuch Footnote 29: 'see also Gerland and Traümuller': corrected to Traumüller