Laboratory at St. John's College, Oxford. 



179 



permission to erect an additional room near the laboratory, in 

 such a position that I could drive the bellows in the new room 

 by a belt from the old shafting, running through the windows. 

 Permission was accorded; and the new room is now in process 

 of erection. When it is finished, I hope to make a more 

 thorough examination of the phenomena in question in the 

 direction indicated in the above paper. 



The engine originally employed proved to be defective, in 

 consequence of its excessive consumption of steam. A small 

 2-horse-power vertical engine has been substituted for it. 

 This is amply sufficient for the work required ; and the steam 

 available is more than enough. The engine is now kept going 

 the whole of every working day; and it is consequently always 

 available for any work that may be required. 



The bellows suffered materially from the high temperature 

 generally maintained in the laboratory. It has now been 

 remade, and the table on which the slides work has been 

 leathered. It answers well under these conditions, admitting 

 of the employment of a heavy wind for mechanical purposes, 

 such as it would hardly have borne in its original form. 



A few words may be not out of place on the question of 

 leathering the table. This practice is never resorted to as a 

 rule by English organ-builders, but always by German 

 builders. English builders consider that they can plane all 

 the surfaces concerned so perfectly that leathering is un- 

 necessary. In actual organ-work small channels are also 

 resorted to, to carry off any wind that may escape between 

 the planed surfaces. However this may have answered with 

 old English organs, in which a very light pressure of wind 

 was employed (generally about 2 inches of water), it certainly 

 fails to give satisfactory results with the heavy pressures now 

 constantly used ; and I am of opinion that the tables ought 

 to be leathered much more generally than is the case. In 

 such an instrument as my bellows I consider the leathering of 

 the tables to be essential. 



There is another point of importance. When the bellows 

 is loaded beyond a certain point (in my instrument to about 

 8 inches of water), the action of the escape-valves when the 

 bellows is full gives rise to vibration. It is proposed, in order 

 to get rid of this, to adopt a form of escape-valve made in two 

 pieces, so that a small bit at the end of the valve is lifted first, 

 and then the valve itself later. In this way the sudden shock 

 which causes the vibration will probably be got rid of. But 

 the load of 7 inches is sufficient for all purposes at present; 

 and the improvement in question will be only with a view to 

 the general perfection of the instrument, 



