816 Directions for constructing 
minute or irregular, must be occupied by fresh air, which, 
when permitted to escape, will carry off impurities with 
it. And thus, by stopping and opening such vents repeat- 
edly, no part of the cargo could miss of purification, and 
this perhaps may be the best mode of administering it. 
Prevention is better than a cure. 
In a vessel equipped with the apparatus described, the 
inattention must be great, if the corn be suffered to sus- 
tain any injury at all. By an early use of it, perspiration 
and damps will presently be dried away ; heating of 
course will be prevented ; and even the production of 
tlie pernicious grub alluded to : for, be the nidus of its 
eggs ever so productive, their embryos will not vivify^ 
without moisture to sustain them. Wherefore, it should 
seem that the corn- merchant in future will have little to 
fear, save the influx of sea- water ; and even this (if in 
small quantities) will, by the frequent use of the ventila 
tor, gradually dry away. 
No. 41. 
Directions for constructing a cheap Bed and elastic 
Frame, for the easy conveyance of sick or wounded 
Persons . Invented , and most humbly presented to his 
Boyal Highness the Commander in Chief By Patrick 
Crichton, Lieutenant -colonel of the Second Begun ent 
Royal Edinburgh Volunteers . 
(With a Plate.) 
Directions for the Construction of the Elastic Frame , 
REFERENCES. 
THE lower frame A A (Plate 9, fig. 8,) is made of ash 
or elm, seven feet long, and five feet four inches broad. 
