380 Philosophical Transactions. 



On the derangement of certain transit instruments by the effects 

 of temperature. By Robert Woodhouse, A.M., F.R.S., &c. 



On some of the compounds of chromium. By Thomas Thom- 

 son, M.D., F.R.S. L. and E., Professor of Chemistry, Glasgow. 



Rules and principles for determining the dispersive ratio of 

 glass; and for computing the radii of curvature for achromatic 

 object-glasses, submitted to the test of experiment. By Peter 

 Barlow, Esq., F.R.S. , Mem. Imp. Ac. Petrop, &c. 



On the change in the plumage of some hen-pheasants. 6y 

 AVilliam Yarrell, Esq., F.L.S. Communicated by William Mor- 

 gan, Esq., F.R.S. ^ 



On the secondary deflectiong produced in a magnetised needle 

 by an iron-shell, in consequence of an unequal distribution of 

 magnetism in its two branches. First noticed by Captain J. P. 

 Wilson, of the Honourable East India Company's ship Hythe. 

 By Peter Barlow, Esq., F.R.S., Mem. Imp. Sc. Petrop. 



On the difference of meridians of the royal observatories of 

 Greenwich and Paris. By Thomas Henderson, Esq. Commu-^ 

 nicated by J. F. W. Herschel, Esq., Sec. R.S. 



Some observations on the effects of dividing the nen^es of the 

 lungs, and subjecting the latter to the influence of voltaic elec- 

 tricity. By A. P. W. Philip, M.D., F.R.S. L. and E. 



On the effects produced upon the air-cells of the lungs when the 

 pulmonary circulation is too much increased. By Sir Everard 

 Home, Bart, V.P.R.S. 



Theory of the diurnal variation of the magnetic-needle, illus- 

 trated by experiments. By S. H. Christie, Esq., M.A., F.R.S. 



On the ultimate composition of simple alimentary substances j 

 with some prehminary remarks on the analysis of organized bodies 

 in general. By William Prout, M.D., F.R.S. 



A Practical Treatise on the use of the Blowpipe in chemical 

 and mineral analysis ; including a systematic arrangement 

 of simple minerals^ adapted to aid the student in his pro- 

 gress in mineralogy , by facilitating the discovery of the 

 names of species. By John Griffin, Author of Chemical 

 Recreations. Glasgow, 1827. 



Performing with the blowpipe is something like playing 

 upon the fiddle — it looks mighty easy, but for its perfect 

 accomplishment requires a combination of skill and dexterity 

 which practice alone can confer. We are disposed, therefore, 

 to think lightly of those essays upon the subject which pre- 

 tend to instruct the beginner in the actual use of the instru- 

 ment ; telling him how he is to puff out his cheeks, breathe 

 through his nose, make a valve of his tongue, and keep up a 



