[ 82 ] 
Telephium repens folio non deciduo. C. B. P. 
287. 
1646 Thalidtrum minus alterum Parifienfium fbliis 
craffioribus et lucidis. H. R. Par. 
1(^47 Tithymalus maritimus. C. B. P. 25)1. 
Tithimalus paralius. J. B. 3. 674. 
1648 Trifolium Bitumen redolens. C. B. 3;7. 
1645) Trifolium Bitumen redolens angulfifolium. 
Boer. Ind. Alt. 2. p. 32. 
Trifolium bituminofum arboreum anguftifo- 
lium ac fempervirens. Hort. Cath. 
Virga aurea Canadenfis folds carnolis non fer- 
ratis latioribus. Hift. Oxon. 
XIX. A Letter to the Right Honourable 
George Lari of Macclesfield, Prefedent of 
the Royal Society, on the Advantage of 
taking the Mean of a Nu7nber of Obfer- 
vations^ in praBical Aflronomy : By 
T. Simp Ton, L\ R, S, 
My Lord, 
Read April lOj'y T is well known to your Lordfhip, 
‘ 755 - ^ method pradtifed by aftrono- 
mers, in order to diminilh the errors ariling from the 
imperfedions of inftr uments, and of the organs of fenfe, 
by taking the Mean of feveral obfervations, has not 
been fo generally received, but that fome perfons, of 
confiderable note, have been of opinion, and even 
publickly maintained, tlut one fingle obfervation, 
taken 
