342 Prof. Bessel's Additions to the Theory of Eclipses, 



The whole of the foregoing remarks are submitted, with 

 much deference, to the consideration of geologists ; as sup- 

 plementary to Dr. Macculloch's memoirs on the concretionary 

 structure in rocks, and as hints, for future investigation, by 

 those who have it in their power to institute extensive re- 

 searches in Geology. 



Hazelvvood School, near Birmingham, 

 Oct. 10th, 1830. 



LI. On the Discharge of a Jet of Water under Water. By 

 R. W. Fox, Esq. 



To the Editors of the Philosophical Magazine and Annals. 



AM not aware that it has been before noticed, that a jet 

 of water discharges the same quantity, in water, as in air, in 

 a given time, without reference to the depth or the motion of 

 the water ; at least within certain limits. 



Thus when the experiment was tried with a head of water 

 six feet high, the same orifice discharged equal quantities in 

 equal times in air, in still water, and in a rapid stream, mov- 

 ing at the rate of about six feet in a second ; the jet having 

 in one case been turned with the current, and in another 

 against it: and when by lengthening the tube, the aperture 

 was submerged to the depth of fifteen feet, the effect was the 

 same as at the surface, under the pressure of an equal co- 

 lumn above it. 



These results have been obtained by my brother Alfred 

 Fox, and myself; — and you may, perhaps, think them de- 

 serving a place in your Magazine, if they should appear to 

 you to be new. 



We sometimes coloured the water, when the jet appeared 

 to pass unbroken to a considerable distance under the water. 



Falmouth, 10:h month, 9th, 1830. K. W. Fox. 



LI I. Additions to the Theory of Eclipses, and the Methods of 

 calculating their Results. By Professor Bessel. 



[Continued from page 275.] 



[7.] HPHE calculation of an occultation of a star can now be 

 *■ performed, after the preparatory operations explained 

 in the preceding section, in two different ways. The first sup- 

 poses that the same value of T is to be applied to all obser- 

 vations which are to be calculated, in which case p and cj cor- 

 respond to the value a in the arrangement above given. On 



this 



