222 l?istructio7isfor the Scientific Expedition 



sphere, if possible, at the four periods, 3 a.m., 9 a.m., 3 p.m., and 



9 P.M. 



The tenth compartment is appropriated to remai'ks on the clouds, 

 and weather generally ; and in the eleventh is to be noted, at noon, 

 the longitude and latitude at sea. 



On a careful review of the month's observations, the maxima 

 and minima results should have the algebraic signs + and — respec- 

 tively affixed. 



The second form is devoted to the corrected results of the obser- 

 vations, and to the optical comparison together of some of them, by 

 their projection upon a scale of equal parts. 



The upper half of the sheet is vertically divided into two equal 

 parts, each prepared for half the month's observations, and accord- 

 ingly ruled acKOSs into sixteen spaces for the daily observations, and 

 two for the sums and means of the quantities. Each half is also 

 divided into five compartments. 



The first is for the date of the month and the phases of the moon. 



The second for the corrected height of the barometer at 32° Fahr. 



The third is appropriated to the elastic force of the aqueous vapour 



corresponding to the dew-point, and which may be taken from 



Table 5. in the Appendix B. 



The fourth is for the maximum and minimum of temperatui'e, and 

 the mean of the two. 



And the fifth for occasional remarks. 



The lower half of the sheet is also vertically divided into two equal 

 parts, each of which is similarly divided into 31 columns for the daily 

 observations of a month ; and these again subdivided into four, for 

 the six-hourly observations of each day. The vertical lines thus 

 formed are divided into 6 inches ; and each inch into tenths of an 

 inch, and half-tenths, by horizontal lines. 



The left-hand compartment thus ruled, is intended for the projec- 

 tion of curves of temperature ; for this purpose each tenth of an 

 inch upon the scale must be reckoned a degree, which will be divided 

 by the faint line into halves. 



The value of the degree may be arbitrarily fixed, and inserted in 

 the margin according to convenience. Towards the upper part of 

 the scale the results of the six-hourly observations should each be 

 marked by a dot in its appropriate space, and the dots may be after- 

 wards connected by a line. 



The temperatures of the dew-point, or of the wet-bulb thermo- 

 meter, or the mean temperature, may be compared with this primary 

 result by projecting their curves in a similar way beneath it ; and 

 should the observations of these points be less frequent than four 

 times in the day, the daily spaces may easily be divided accordingly. 

 The right-hand compartment is appropriated to the projection of 

 curves of pressure, and the four daily observations of the barometer 

 are to be marked by dots towards the upper part of the scale of 

 inches, and afterwards connected by a line. Towards the lower 

 part of the scale the elastic force of the vapour is to be noted, and 

 the marks to be similarly connected by a line. 



