SSi ^Penetration into Space hy Tele/copes. 



" It has fevcral ftars in it; they arc however fo fmall that I can but juft perceive fome, 

 " and fufpe£l others." 

 May3i^i783. The fame nebula with a lofect reflc£lor ; penetrating povirer 



" With a magnifying power of 250, it is all refolved into ftars ; they are very clofe, 

 " and the appearance is beautiful. With 600, perfedly refolved. There is a confide- 

 " rable ftar not far from the middle ; another not far from one fide, but out of the clufter; 

 " another pretty bright one ; and a great number of fmall ones." 



Here we have a cafe where the penetrating power of 20 fell fhort, when 29 refolved the 

 nebula completely. This obje£t requires alfo great magnifying power to Ihew the ftars of 

 it well; but that power had before been tried, in the 7-feet, as far as 460, without fuc- 

 cefs, and could only give an Indication of its being compofed of ftars; whereas the lower 

 magnifying power of 250, with a greater penetrating power, in the 10-feet inftrument, 

 refolved the whole nebula into ftars. 



May 3, 1783." I viewed the nebula between Vi and j Ophiuchi, difcovered by Mr. 

 Meffier, in 1764. 



" With a lo-feet refle£l:or, and a magnifying power of 250, I fee feveral ftars in it, 

 *' and make no doubt a higher power, and more light, will refolve it all into ftars. This 

 " feems to be a good nebula for the purpofe of eftablifhing the connedlon between nebulae 

 " and clufters of ftars' in general." 



June 18, 1784. The fame nebula viewed with a large Newtonian 20-feet refleftorj. 



a/ 1 o V T 88"^ 9 T * 



penetrating power — !Z2 = 61,18 ; and a magnifying power of 157. 



2 



" A very large and very bright clufter of excefllvely compreffcd ftars. The ftars are but 

 " juft vlfible, and are of unequal magnitudes : the large ftars are red ; and the clufter is a 

 " miniature of that near Flamfteed's42dCom3e Berenices. RA i"]^ 6 32"; PD 108° 18'." 



Here, a penetrating power of 29, with a magnifying power of 250, would barely fhew 

 a few ftars i when, in the other inftrument, a power 61 of the firft fort^ and oiJy 157 of 

 the latter, (hewed them completely well. 



July 4, 1783. I viewed the nebula between Flamfteed's 25 and 26 Sagittaril, difco- 

 vered by Abraham Ihle, in 1665. 



" With a fmall 2o-feet Newtonian telefcope, power 200, it is all refolved into ftars, 

 *' that are very fmall and clofe. There muft be fome hundreds of them". With 350, I 

 " fee the ftars very plainly ; but the nebula is too low in this latitude for fuch a power." 



CTo be concluded in our tiext.) 



