| Description | Table of mean hourly deflections in electrical currents in telegraph wires between Derby and Birmingham, detected in Derby by 'deflectometer' [galvanometer]. Commencing at 1.00am on 17 May, and ending at 12.00 midnight on 23 May 1847. Columns for time of observation, left and right deflections on each day, with a mean of each observational hour over the seven day period.
Data on magnetic deflections in the Midlands was used in the paper 'On the spontaneous electrical currents observed in the wires of the electric telegraph', by W.H. Barlow, Philosophical Transactions of the Royal Society, v.139 (1849), pp.61-72.
Headed [p.1]: 'Table no.2. Mean deflections of each hour exhibited by a deflectometer at Derby in connection with a wire extending to Birmingham, for the week commencing May 17 1847...Birmingham Instrument'. Note below the main table: 'Previous to taking the observations given in this table the deflectometer had been rendered highly sensitive by diminishing the weight of the lower end of the needle...'. |