464 



NA TURE 



[September 30, 1922 



An Optical Sonometer. 



/^XE form of an optical sonometer recently made by 

 ^—^ Messrs. Adam Hilger, Ltd. (of 75A Camden Road, 

 N.W.l), is shown diagrammatically in Fig. 1. The 



apparatus is designed to record the pressure variation 

 caused by sound waves. It consists of a diaphragm 

 box B, to which is attached a horn for receiving 

 sound waves. In box B is a 

 diaphragm with a platinised, 

 silvered, or gilt inner face; this 

 is the actual receiver. Recording 

 the vibrations produced in the disc 

 is accomplished by means of a 

 beam of light directed from the 

 source D (a Pointolite Lamp of 

 30 or 100 candle-power) by a con- 

 denser E through the slit F and brought to a focus on 

 the diaphragm C. Thence by means of lenses G and H 

 an image of the slit is formed on the photographic paper 



or film on the drum J. The lens H being cylin- 

 drical with its axis parallel to the drum, the beam 

 of light is brought to an intense point image on 

 the drum, and as the latter rotates a record of 

 the deflection of the diaphragm is obtained. The 

 spot of light can be focussed on the drum at any 

 distance from 4 to 20 inches according to the 

 amplitude of vibration under investigation and 

 the degree of magnification consequently re- 

 quired. 



Some of the models constructed are fitted with a 

 camera into which the film is loaded through a small 

 aperture at the back, while an arrangement for visual 

 observation of the sound wave is also included. The 

 revolving drum, on which the record of the vibrations 

 is made, is enclosed in a specially designed camera 

 with an automatic shutter ; by this means any 

 fraction of the drum, from one-sixth to one complete 

 revolution, can be exposed according to the type of 

 record which it is desired to make. 



Records of various sounds have been made with the 

 apparatus, e.g. for whistling at a frequency of about 

 1300 per second, singing at about 200 per second, and 



Fig. 2. 



of the sound produced by a leather-covered mallet 

 on wood. This last is shown in Fig. 2, the frequency 

 being about 250 per second. 



The Rowett Research Institute, Aberdeen. 



THE Rowett Institute, which was formally opened 

 by Her Majesty the Queen on September 12, 

 had its origin in the scheme of research in agriculture 

 adopted by the Development Commission in rgn. 

 Under that scheme provision was made for the 

 establishment of one or more Institutes to carry 

 out research in each of the branches of agricultural 

 science. It was decided to establish two Institutes 

 for the study of Animal Nutrition, one at Cambridge 

 and one in Scotland. In 1913 a Joint Committee 

 representing the University of Aberdeen and the 

 North of Scotland College of Agriculture was con- 

 stituted to act as a governing body for the Scottish 

 Institute. Preliminary work was begun in 1914, 

 but was stopped by the war. In 1920 the scheme 

 for the development of the Institute was approved 

 by the Board of Agriculture for Scotland and the 

 Development Commission, and the erection of the 

 buildings began early in 1921. The buildings are 

 now practically completed, except for the fitting up 

 of one or two of the laboratories. 



In determining the nature of the Institute to be 

 established it was recognised that the basis of prai tii al 

 experimental work is the researches of the purely 

 scientific worker. Provision was therefore made for 

 work in those branches of science that constitute 

 animal nutrition. The Institute was planned to 

 consist of the following departments : physiology, 

 biochemistry, bacteriology, and pathology, which are 

 housed in the one main building, and animal husbandry, 



NO. 2761, VOL I IO] 



I which consists of an experimental stock farm with 

 I buildings adapted for conducting feeding experiments. 

 To facilitate the collaboration of those engaged in 

 laboratory researches and those carrying out feeding 

 experiments, the main building containing the labora- 

 tories has been erected on the experimental farm. 

 This enables the workers to be in daily contact with 

 each other, and to be conversant with the different 

 aspects of the problem or group of problems on 

 which the Institute is engaged. 



The experimental farm is situated on the out- 

 skirts of Aberdeen, within easy access of tramway 

 and train. The building containing the laboratories 

 is built of granite and is 156 feet long by 45 feet 

 deep in the central block and 39 feet deep in the 

 wings. It consists of two floors and a basement. 

 The biochemical department, tire calorimetry room, 

 the aseptic room, and certain other rooms occupy 

 the ground floor. The physiology and the bacteri- 

 ology and pathology departments are on the first 

 floor. In the west wing of this floor is the adminis- 

 trative department, rooms for filing records and 

 statistics, and the library. About 30 yards west 

 of this building are the experimental farm buildings 

 which have a floor area of about 1500 square yards. 

 The part nearest to the building containing the 

 laboratories is occupied by two rooms, where animals 

 under metabolic experiment can be kept in cages. 

 The rest of the building consists of food stores, 

 food preparation rooms, and stalls and pens for the 



