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Suggestions for the better Ventilation of Sailing and Steam 

 Vessels. By Robert Ritchie, Esq., F.R.S.S.A., &c., Civil- 

 Engineer, Edinburgh. (Communicated by the Royal 

 Scottish Society of Arts.)* 



The importance of ventilation, as regards ships, while it 

 has not escaped the notice of scientific men in the past as well 

 as the present time, appears never to have received sufficient 

 public attention, although, if there is one place more than 

 another in which the salubrity of the air is most essential, it 

 is on shipboard. Its great importance, indeed, must be suffi- 

 ciently apparent, when the navy of Britain, the enormous ton- 

 age of her mercantile marine, and the great number of men 

 therein employed, are considered. 



The confinement in the lower decks and close cabins of 

 ships, which are often crowded with many persons generally 

 both eating and sleeping there, cannot be avoided, and 

 admits of little alleviation. In dwelling-houses, if the air 

 be vitiated, doors and windows may be opened, and thus a 

 current of fresh air may be allowed to pass through them, 

 while in winter the open fire acts to a certain extent as a me- 

 dium of ventilation. Very different is a crowded vessel in a 



published in the Philosophical Transactions for 1822, he has given an observation 

 made by him of "Venus, when the planet was 53 minutes distant from the sun. 

 The telescope which he used was a small one of seven inches focal length, and 

 one inch aperture. He has also given directions for rendering the planet visible 

 at a less angular distance from the sun. 



The reason why Venus is not observed near the superior conjunction with the 

 meridian instruments in fixed observatories, is the necessity of employing trouble- 

 some apparatus for keeping oflf the sun's light, and the comparative inutility of 

 such observations. 



Measurements of Venus' diameter about the superior conjunction would be 

 useless. On account of the small apparent magnitude of the planet at that time, 

 and its proximity to the sun, it would be in the worst situation for the attain- 

 ment of accuracy. A difference between the polar and equatorial diameters would 

 be inappreciable, for, at the utmost, it can only be a small fractional part of the 

 unavoidable errors of observation. 



It may be added, that the planet Mercury has also been seen by M. Vidal at a 

 very small distance from the sun. — Edit. 



* (Abridged from a paper Read before the Royal Scottish Society of Arts, 

 April 10. 1843, Illustrated by Diagrams and Models.) 



