306 Specific Gravity and Strength of Stones. 



But whatever excuse may be made for omitting the bulk 6f 

 such things in our National Ep'iemeris, every one must be sensi- 

 ble of the importance and propriety of having all those phaeno- 

 mena carefully computed which are thonght worthy of beingj in- 

 serted : and it is to this point more particularly that I wish to 

 call the attention of your readers. It was aiuiounced in the 

 Nautical Almanac that, last night, tliere would be an occultation 

 of a. Lilrce; and I accordingly made every preparation for ob- 

 serving it. But what was my surprise to find that the border 

 of the moon did not approach within ten or twelve minutes of 

 the star ; and that consequently no occultation took place ! This 

 'fact led me to suspect the accuracy of the notice for the ensuing 

 month (May), where an occultation of the same star is an- 

 nounced on the 2Sth. It is true that an occultation of that star 

 will take place on that day ; but it will happen near an hour 

 sooner than the time set down in the Nautical Almanac. Indeed 

 the emersion of the star will actually take place above eighteen 

 minutes before the time set down in the Nautical Almanac as 

 the commencement of the occultation. So that those persons 

 who depend on the time in the Nautical Almanac, will be de- 

 prived of the opportunity of observing this interesting and beau- 

 tiful appearance. 



The following comparison of the apparent times of the phae- 

 iiomenon above alluded to may, perhaps, be interesting to se- 

 veral of yoxir readers. 



u^ccord'mg to the Nautical Abnanac. 



Im. 9''2'i . lO'Ai , 



T- ^f\ Aj * OT J- -^o. or the moon s centre. 



Em. 10 4 1: ^4 > 



According to my Calculation, 



Im. S'- 12' ^ 15'|>c (.^ ' , 



,, o Aat * oi J- feo. ot the moon s centre. 

 Lm. 8 464 o\ ^ 



I have already stated that the time of the conjunction of the 

 moon with /3 Scorpionis is incorrectly stated : the same remark 

 will apply to the conjunctions of Jupiter with the same star on the 

 14th of July and the 1 0th of August ; neither of which will take 

 place. It is evident that the computer has assumed the longi- 

 tude of the star greater than it really is. - 



1 am, sir, your constant reader, 

 April 4, 1817. AsTRONOMICUS. 



SPECIFIC GRAVITY AND STRENGTH OF STONES. 



To Mr. Tilloch. 

 Sir, — The article on the strength of ttones, in your last num- 

 ber, io not correct in ascribing the experiments to Gauthey. 



They 



