288 Miscellaneous Intelligence. 
knowledge of the phenomena relating to the pendulum, is the following: 
—Tum animadvertam (considerata hypothesi Terrse mote) in una pen- » 
duli oscillatione non describi ab ejus centro perfecte unum eundemque 
arcum in plano eodem: nihilo tamen secius cum nascentes inde differ- 
entiz rem meam non turbent, negligi a me tuto possunt; sufficitque hee 
semel indicavisse, etc. ' 
In M. Secchi’s experiments with the pendulum he obtained the mean 
hourly deviation 9° 53’ 16”. The calculated deviation for the latitude 
of Rome is, for an hour of sidereal time, 10° 1! 2/7. 
hold both, for the film slips about very easily. Blotting paper will then 
absorb some of the superfluous water, and the remainder may be forced 
out by rubbing slightly, but always in one direction. By drying the 
whole under pressure the picture will be found firmly adherent to the 
will, of course, affect the faithfulness of the image. 1 am, &c., 
Royal Institution, Edinburgh. E. W. Dattas. 
Mr. Archer has been in the habit of separating the film of collodion 
from the glass and transferring it to paper; but it appears to us tha 
there are some valuable suggestions in our correspondent’s note. 4 
: a Lunar Rainbow; by C. M. Tracy, (from a letter date 
Lynn, Mass., Aug. 1, 1852.)—Friday, July 30, at 8h. 10m. P. M., 
fine lunar rainbow was observed here, formed by the newly risen er 
at the close of a slight shower. The arch was without interruption on 
beautifully distinct; being placed against a heavy cloud which occup'e? 
the western sky. Slight prismatic tints were discoverable at one me 
