The Culture of Greenhouse Orchids 



the amount varies with the angle. Thus it has 

 l.ieen shdwn that of a given quantity of light fall- 

 ing perpendicularly upon a given point, one-fifth is 

 absorbed or intercepted by the atmosphere ; if it 

 fall at an angle of 50', more than one-fourth is 

 absorbed ; and at an angle of 75", fully one-half. 

 Hence in the winter months, even when the days 

 are clear and bright, we can get nf> more than five- 

 eighths of the solar light these New Grranadan 

 Cattleyas receive in their native country, on the 

 assumption that other circumstances remain the 

 same." But they are far from the same. The tropic 

 sun breaks through continually during the rainy 

 months. And what proportion of our winter days 

 are clear and bright ? 



It follows that every effort should be made to 

 secure such light as we may command, especially 

 in winter. 



The natural habit of orchids to grow during the 

 dull season and rest diiring the heat of summer 

 could not possibly be permitted in this latitude. 

 We must needs call upon them to reverse the 

 process, and they consent without the smallest 

 difficulty ; in fact, if their wants be properly 

 supplied, the most of them will grow more strongly 

 than at home. Our light is deficient, but then our 

 day is far longer. They gain not less than two 



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