222 BULLETIN 139, UNITED STATES NATIONAL MUSEUM 



an increasing demand for light among the northern nations as culture 

 grew, but inventions which would foreshadow the effective lamp can 

 scarcely be distinguished among the barbarous lights of the Middle 



Ages. 



LAMPS WITH LIMITED GRAVITY PRESSURE 



The link in the chain of lamps from the Roman period to the 

 period of enlightened invention is the Italian lucerna (pi. 41, fig. 2). 

 This lamp is of bronze, brass, or terra cotta, and consists of a res- 

 ervoir with from two to four spouts and an upright stem with base 

 on which the perforated reservoir can be raised or lowered. When 

 the reservoir is full there is a slight gravity head on the oil, not con- 

 clusively intentional but which might suggest an improvement to an 

 observing mind. In passing it may be said that the Italian lucerna 

 is the most graceful and beautiful lamp ever designed. 



There follow in this apparent hne lamps patently designed to 

 to furnish oil to the wick under gravity pressure (pi. 41, figs. 1,3, 4). 

 Tliis series of lamps is selected from the numerous primitive or quasi- 

 primitive lighting devices of Europe as the one pointing out the way to 

 the practicable lamp. Up to a few years ago these slanting long spout 

 lamps in brass and copper were in use in Belgium, France, and other 

 north European countries. Many came with immigrants to the New 

 World. 



In the beginning complexities of researches ushering in the inven- 

 tive period many experiments were carried on by men whose minds 

 belonged to a new age. The needs for more hght were stressed by 

 growing cities, navigation, commerce, occupations, and the vast 

 ramifications of social intercourse. Civic fighting was beginning, 

 and provisions must be made looking toward efficiency and economy 

 in public illumination. There was also evident the remuneration 

 which would follow the appearance of practicable lighting apparatus. 

 The lamp, which for ages had been childishly simple, required for its 

 elevation to the plane of science the attack of profoundly complex 

 problems in many lines. It is appreciated now that the effective 

 lamp required the services of chemistry, physics, mechanics, the 

 industrial arts and sciences, and only by their progress was it possible to 

 transform the grease cup, which our ancestors thought the last word 

 in lighting, into an efficient illuminating apparatus. 



The requirements were as follows: 



1. A limpid combustible fluid, abundant and cheap. 



2. A designed wick of strong capillarity and free burning without 

 too much carbon residue. The fluid and the wick are thus comple- 

 mentary. 



3. Aeration of the flame by controlled draught. The fluid, wick, 

 and draught are mutually complementary. 



