GROWTH OF PLANTS IN WARD'S CASES. 139 



297. These observations point out the great injury which is caused 

 to plants by the gases given off during the combustion of coal, and 

 more especially by certain chemical works. In the vicinity of the 

 latter, the vegetation, for a considerable distance around, is often 

 destroyed, particularly in the direction of the prevailing winds of the 

 locality. The atmosphere of large manufacturing towns, in which 

 fuliginous matter and sulphurous gases abound, is peculiarly hurtful 

 to vegetable life. In order to protect plants from such prejudicial 

 influences, Mr. N. B. Ward has invented close glass Cases, in which 

 plants can be made to grow independently of the noxious atmosphere 

 around.* These Cases consist of a trough containing soil, and a frame 

 of glass, which is accurately fitted upon it. The soil is well supplied 

 with water at first, and after the plants are put in they are kept exposed 

 to the light. In these circumstances, they will continue to thrive for 

 a long time, even for years, without any fresh supply of moisture or 

 any direct exposure to the air. They are peculiarly fitted for rooms 

 where the dryness of the atmosphere interferes with the vigour of 

 plants, by causing greater exhalation than can be compensated by 

 the absorption of moisture by the roots. Some tribes of plants, as 

 Ferns, requiring a humid atmosphere, thrive well in such Cases. The 

 windows of houses may be converted by this means into conservatories. 

 Those who wish to see the effects thus produced, ought to visit Mr, 

 Ward's house, in Wellclose square, London. Nothing can exceed 

 the beauty and luxuriance of his Ferns. 



298. But it is not merely as matters of luxury and curiosity that 

 these Cases deserve notice. They serve as a most important means of 

 transporting plants, in a living state, to and from foreign climates; and 

 they are in constant use for that purpose. Plants have thus been brought 

 to this country which could not have retained their vitality in the form 

 of seed, and which would have been destroyed by exposure to the 

 sea-breeze and to the vicissitudes of climate experienced during their 

 transport. The stillness of the atmosphere in the Case contributes 

 materially to prevent injurious consequences. In June 1833, Mr. 

 Ward filled two Cases with Ferns, Grasses, &c., and sent them to 

 Sydney, where they arrived in January 1834. The plants were 

 taken out in good condition, and the Cases were refilled at Sydney, 

 in February 1834, the thermometer then being between 90 and 

 100 Fahrenheit. In their passage to England, they encountered 

 very varying temperatures. The thermometer fell to 20 on round- 

 ing Cape Horn, and the decks were covered a foot with snow. In 

 crossing the line, the thermometer rose to 120, and fell to 40 on 

 their arrival in the British channel in the beginning of November, 

 eight months after they had been enclosed. The plants were not once 



* See Ward on the growth of plants in closed Cases. 



