Registering and Printing Barometer. 13 



locked together, and it is just as impossible for it to get 

 out of order as it is for ordinary clock gearing. 



The chief merit of this combination is, that it will carry 

 for ten either forwards or backwards. This principle is 

 necessary in any meteorological printing instrument. We 

 need no extra apparatus for bringing the type in line, since 

 if the mechanism is well constructed, it will always arrange 

 itself. When once set it will remain so, for no change can 

 be made without ungearing the machine. 



We use ordinary type which are set in separate disks, 

 being afterwards screwed fast to w, t, and h. In case a 

 type is accidentally damaged, or broken, another can be 

 inserted in a few minutes. Steel type would undoubtedly 

 be the best, as being more durable and less liable to dam- 

 age. We should add, that the wheels t and b have each 

 50 teeth ; five teeth being moved at one impulse. 



The printed results are received on the strip of paper j, 

 moved by the clock-work k, fig. 3, which at the same time 

 regulates the revolving cylinder o, on which is traced the 

 curve of pressure. This same clock raises a small hammer 

 A, by means of a screw or spiral on the minute wheel 

 arbor, which at every revolution is allowed to strike the 

 small cushion i, by that means leaving the impression of the 

 type on the paper strip. In order to secure greater distinct- 

 ness in the printed results, without employing much power 

 to make the impression, a strip of duplicating impression 

 paper is inserted between the type and ordinary sheet of 

 white paper. 



We are not limited in our printing to hourly records, 

 but they can be obtained as often as it is desirable, by 

 supplying the additional power required to raise the ham- 

 mer. The clock for moving the printed slip and cylinder 

 is an ordinary half-second's pendulum, which we happened 

 to have at hand. It was not thought necessary to print 



