2IO 



NATURE 



{July 12, 1877 



ourselves can testify, forms a thoroughly comfortable and 

 secure bed or lounge. Mr. Stanley, we believe, was so 

 favourably impressed with the hammock, that he has 

 taken a supply with him in his present exploration ; and 

 lor explorers iu tropical countries, we should think it would 

 prove useful in many ways, as it can not only be used as 

 a bed, but, mounted on a pole, as a travelling litter or 

 palanquin. For those of our readers engaged in explorations 

 of any kind, geological, geographical, botanical, zoological, 

 or even in doing an ordinary tour, in remote districts, we 



NCING APPARATUS. 



believe the hammock would be found of real service, as it 

 would make them quite independent of sleeping accommo- 

 dation, and would not increase the weight of their 

 impedimenta by very many ounces. An idea of its 

 construction and its adaptability to almost any cir- 

 cumstances may be obtained from the illustrations we 

 give. We can honestly recommend the hammock as 

 likely to answer all the purposes for which it has been 

 designed. 



THE SANITARY INSTITUTE 

 n^HE lecture by Dr. Richardson, published in our issue 

 •*- of last week, has called public attention to the 

 Sanitary Institute of Great Britain, before which the 

 lecture was delivered. The Institute was founded in 

 July, 1876, at a public meeting held at St. James's Hall, 

 and presided over by his Grace the Duke of Northum- 

 berland. The Institute has for its work a wide range of 

 subjects. It has sprung, we may say, out of the necessi- 

 ties of the time, and in the first instance may be considered 

 as a nucleus round which will cluster the many men of 

 science who are now employed in carrying out the execu- 

 tive sanitary or health work of the kingdom. The various 

 medical officers of health, the certifying surgeons under 

 the Factory Acts, the engineers and sanitary surveyors of | 

 different localities, the mayors of municipalities, and the I 

 chairmen and presidents of local boards, all of these must I 

 needs take an interest in and in time form the body cor- 

 porate of an institution framed for the purpose of becoming 

 as it were a voluntary health p.arliament. In addition to 

 these sections of the Institute there are many other sections I 

 of the community which will, we should think, earnestly [ 

 join in the work. For reasons plainly stated by Dr. 

 Richardson ladies are invited to take part in the proceed- j 

 ings and to help forward sanitary progress. We feel 

 sure there will also be a large class of active men ! 

 unconnected professionally with sanitary work who will 

 be ambitious to take a part in the great practical scientific 

 labour of the time, the only labour we may say in which 

 science lends herself immediately to the aid and comfort 

 of domestic life and felicity. 



The detailed work of the Sanitary Institute has been 

 in some measure projected by its founders ; but it is more 

 than probable that in the course of its natural development 

 it will grow into something different from that which is 

 now supposed. At the same time we are bound to say 

 that the plan is sufficiently simple and practical to 

 warrant the expectations of those who have mapped 

 it out. The objects we have seen proposed are all 

 diiected to some useful and desirable end. To obtain 

 a registration of the diseases of the kingdom ; to 

 establish communications with medical officers, of health ; 

 to form local branches of the Institute throughout the 

 kingdom ; to examine and grant certificates of quali- 

 fication to local surveyors and inspectors of nuisances, 

 and to form a register of such certificated officers ; to 



investigate the chemical aspects of the sewage question ; 

 to establish a sanitary exhibition, and to form a library of 

 books on health subjects ; — these objects, some of which 

 must needs become a part of every sanitary organisation, 

 are sufficiently comprehensive to cover any amount of work, 

 and to tax any amount of industry that may be found in 

 the best organised public body. So far the prospects of the 

 Institute are brought beyond what is commontosuch under- 

 takings in their earliest days. Members are daily being 

 added, and an effective Council has been elected. Already 

 one of the provincial towns, Scarborough, has invited the 

 Institute to hold its first provincial Congress there, and 

 in France a kindred society has been formed in sequence, 

 and, it may be said without offence, in imitation of the 

 one already founded in London. The visit of Dr. De Pietra 

 Santa, of Mariii Davy, and other savants from Paris to 

 the meeting on Thursday last, is a significant sign of the 

 good feeling with which the two rival societies have com- 

 menced their labours. 



For our parts we welcome heartily both Institutes, and 

 shall enjoy the privilege of watching their onward pro- 

 gress and recording their success. 



ON THE SOURCE OF THE CARBON OF 

 PLANTS 



NEARLY half the dry substance of plants is carbon ; 

 and it is conclusively established that they derive, 

 at any rate, the greater part of it, directly from the carbon- 

 dioxide of the atmosphere, which the chlorophyll cells 

 have the power of decomposing iu sunlight, at the same 

 time evolving oxygen. But this function of vegetation, 

 which is so essential a complement to the processes of 

 animal life, gives rise to many problems hitherto un- 

 solved ; and an important one is whether or not plants 

 avail themselves of other obviously possible sources of 

 carbon than that existing in such very small proportion, 

 although in large actual amount, in the ambiant air. 



Our knowledge bearing upon the subject as it exists in 

 the present day, is the resultant of careful investigations by 

 many observers. In the last century Bonnet discovered the 

 gaseous exhalation ; Priestley that the gas is oxygen ; 

 Ingenhouz that the oxygen is only evolved in sunlight ; 

 Sennebier that it is due to the decomposition of carbon- 

 dioxide, but he believed that the carbon-dioxide is taken 

 up in solution in w.iter. Early in this century de Saussure 

 carried out a long series of experiments on the relations 

 between the carbon-dioxide decomposed, and the oxygen 

 evolved, and on the amount of carbon-dioxide in the air 

 compatible with the healthy development of plants. Since 

 his time many eminent names have been added to the 

 list of patient labourers in this field of inquiry. 



Boussingault woiked on the question whether the 

 carbon-dioxide is absorbed by the leaves, or taken up by 

 water through the roots ; and by direct experiments 

 proved that the leaves of plants do take up the carbon- 

 dioxide, which is so sparingly, though so uniformly, 

 diffused in the atmosphere. His researches led him to 

 conclude that, by far the greater part, if not the whole, of 

 the carbon which enters into the constitution of the 

 organs of plants is derived from atmospheric carbon- 

 dioxide ; 'and while drawing attention to the fact that, 

 for healthy and vigorous action, plants require large 

 volumes of air to pass over them, and to the surprising 

 rapidity with which they absorb the carbon-dioxide fiom 

 it, he makes calculations as to the surface presented to 

 the air by the leaves of dilTeient crops. Taking the 

 average number of plants growing per hectare (about 2\ 

 English acres), he estimates that : — 



Artichoke gives a surface of 142,410 square metres. 

 Beetroot „ ,, 49.921 ,, „ 



Potato „ „ 39.641 ,) „ 



Wheat ,, ,, 35.490 ,, 



Boussingault also made experiments in regard to the 



