136 SEVENTH REPORT—1837. 
On Mechanical Sculpture, with Specimens. By Joun Isaac HAWKINS. 
On a New Method of obtaining an Artificial Horizon at Sea. 
By W. Errricx. 
On the Application of Steam to Long Voyages. By Dr. LARDNER. 
On the Ventilation of Tunnels. By Witt1am West, of Leeds. 
The writer has found, by experiments repeated under various cir- 
cumstances in the tunnel on the Leeds and Selby Railway, that even 
when the external atmosphere is as near to perfect stillness as is 
common in this climate, an atmospheric current passes through the 
tunnel with sufficient rapidity to prevent the loss from hot air or gain 
from cold of more than a very few degrees; and this takes place almost 
entirely at the entrance, while without rapid transmission it would of 
course soon reach the mean temperature of the spot. 
Sometimes, however, the thermometer shows that the air which enters 
at the windward end passes up the nearest shaft, leaving the remainder 
of the tunnel worse ventilated than if no shaft existed. As the results 
of his experiments, he submits :— 
1. That the legislature and the public need apprehend no danger 
from the stagnation of air in railway tunnels, while they have abundant 
protection in the enormous cost against any company increasing without 
occasion either their number or their length. 
2. That it is at least doubtful whether open shafts do not rather 
impede than promote effectual ventilation from end to end. 
STATISTICS. 
A Brief Memoir of the Growth, Progress, and Extent of the Trade be- 
tween the United Kingdom and the United States of America, from 
the beginning of the Eighteenth Century to the present time. By 
G. R. Porrer, Vice-President of the Statistical Society of London. 
This memoir, after reciting the date of the first settlement of each 
of the British colonies now included in the confederation forming 
“The United States of America,” contains notices, from the writings 
of Sir Josiah Child and others, indicating the nature and extent of the 
commercial intercourse maintained by them with the parent country 
in the years which immediately followed the dates of their settlement. 
Tables are given in an appendix to the memoir, wherein the further 
