11 • 



3. A second thermometer to be used as a wet-bulb thermometer. A knowledge of the moist- 

 ure of the air is well nigh as important as a knowledge of its temperature or weight. Various 

 instnunents have been used for this purpose, but the wet-bulb thermometer is recommended by 

 considerations of economy and convenience. 



4. A pair of self-registering thermometers. 



It is very desirable to know the greatest heat and cold of every day, and we can never be 

 sure of attaming this object without self-registering instruments. Such instrmnents would there- 

 fore furnish most important observations, although the remaining observations woidd still be 

 valuable without them. 



5. A Rain-gauge. 



6. A Vane. 



The vane is a most important Meteorological instrument ; but it is generally so badly made that 

 it may, perhaps, be best for the State to provide them all of uniform construction. The most useful 

 form of an instrument not self-registering is probably the following. Let the vane be firmly attached 

 to an upright revolving shaft, to whose lower extremity is seemed a graduated circle. A fixed index 

 will then point out exactly the direction of the wind at the time of observation. Such an instrument 

 might be provided at very moderate expense. But whatever form be adopted, the cardinal points of 

 the compass should be carefully determined by Astronomical observations ; or by the magnetic 

 needle, in which case allowance should be made for the variation. 



The following is an estimate of the expense of a set of instriunents for a single station. 



A standard barometer made by Newman, of London, costs $ 100. A cheap barometer may 

 be obtained for $ 10. A barometer which will furnish satisfactory results may be obtained for 

 about $20. 



Two thermometers of a good construction wiU cost $2 25 each. A pair of self-registering 

 thermometers will cost $ 5 00. A rain-gauge, $ 2 50 ; makuig the price of one set of instru- 

 ments, #32 00. 



At this rate, the instrmnents for twenty-one stations would cost $ 672 ; but if the instruments 

 now in use at the different Academies are considered sufficiently trustworthy, something might be 

 saved from this estimate. The construction of the instruments should be superintended throughout 

 by some competent gentleman of science, as without good instruments, the labor expended in 

 observing them will be well nigh lost. 



/// The kind of Observations. 

 The observations will of course extend to all the instrmnents furnished ; besides which, certain 



