Page:Handbook of Meteorology.djvu/254

 Indeed, many observers prefer to make dial readings, except in cases where hour totals are required.

The establishment of the time of the daily maxima and the daily minima is a most useful problem for cooperative and volunteer observers to undertake. This is very easily solved from the daily record sheets, but close observation will enable an observer to get pretty accurate results without the aid of instruments. Daily observations may be summarized in monthly



To obviate the inconvenience of changing record sheets at midnight, they are most commonly changed at noon. A day’s record consists of the two lower lines of one sheet and the two upper lines of the sheet for the day following. The aggregates may be kept in half-day totals, but it is better to carry them over and enter them on the record sheet of the following day. The necessary thing is a definite plan followed with intelligence rather than slavish exactness.

Changing anemograph sheets precisely at noon is highly desirable. If the clock is either fast or slow, its rate is best