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In the ereding of an Obfervatory the three principal points 

 are the fitnation, foundation and foil. As the building mul^ 

 neceffarily be low, the fituation fliould be ekvated, command- 

 ing a clear horizon all around, but particularly to 'tlie Morth 



and South. ^ » •'■• •^-^'"--^ "'- 



lumr, adi ni om o) MnabnaJni^ioqui 



That an Oisfe'rvatory 'fli6urd"De loHv', mull appear an odd 

 affertion to fuch as are acquainted with thofe only of the laft 

 century, and not converfant with modern pradice : the prefent 

 refinement of aftrdnomical inftruments, fince the application 

 of telelcopic fights, demands the utmoft ftability. This was a 

 point not to be obtained whilft ' refracting telcfcopes, of the 

 original frame and conftrudlion, were in ufe. The unmanage- 

 able length of tube demanded by the fimple objed glafs, 

 where any tolerable magnifying power was defired, rendered 

 lofty and extenfive piles of building indifpenfable ; but the 

 great invention of refledling ielefcopes by Sir Ifaac Neyvton, 

 and the difcovery of the a'clirbmatic objefl glalfs by Mr. Dbllond^ 

 flill more ufeful when applied to aftronomical innrumenfs, have 

 freed us from the neceffity of introducing thofe lofty piles, by 

 which the courfe of obfervation with'fomS of the moft valu- 

 able inftruments is interrupted, and an Obfervatory injured in 

 many and important refpedls. 



In cohfequ'eric6'of''^lie iiripeffeAion of feleicopes in the' times' 



which r have mentioned, we find thofe great and unflable 



ftrudlures forming an effential part of every Obfervatory built 



at that period, all which are now unneceffary ; and if through 



a weak attachment to old cuftoms they are introduced into 



Obfervatories at prefent, they may add to the magnificence, at 



the expence of the value of the work. 



The 



