Page:William Petty - Economic Writings (1899) vol 1.djvu/269

Rh And since the true and clear knowledge thereof depends upon several long, tedious, and reiterated Observations, simple and comparative, made in the several parts of Ireland, in the several Seasons of the Year, and compar'd with the like Observations, made with the same or like Instruments, in the several parts of the Earth; we must for the present only say, that there are in being the several Instruments following, viz.

1. An Instrument to measure the motion of the Wind, and consequently its strength.

2. How many Hours in the day in the whole year it blows from any point of the Compass.

3. To measure what quantity of Rain falls in the year upon any quantity or space of ground.

4. What air is most desiccative of moistness.

5. What Alterations are made in the gravity and levity of the Air from Hour to Hour. |50|

6. The Thermometer or Weather-Glass of the better sort.

7. The Instrument to measure and foretel Frost and Snow.

Which Instruments many men must make use of in the several parts of Ireland, and the rest of the World, and corresponding with each other, communicate and correct their Observation by Reason.

In the mean time let it suffice to say, that at Dublin the Wind blows 2 parts of 5 from the South-West to the West, one part from South-West to the South; one other from the West to North-East, and the rest from the North-East to the South: 3 parts of 10 between West and South-West $2/10$ between S. W. and S. S. E. $2/10$ between S. S. E. and N. E. by N. $2/10$ N. E. by N. to N. & W. or very near thereabouts.

2. That from the 10th of Septemb. to the 10th of March,