COMMERCIAL FORMS. 709 



brances through me : to hold the same to the said lessor and his assigns 

 forever. 



Witness my hand and seal, this 1st day of April, A.D. 1881. 



Executed in presence of > D UNN,NG. [L. s.] 



R. DOE. S 



Landlord's Agreement. 



THIS is TO CERTIFY, That I have, this first day of April, 1881, let and 

 rented unto Peter Jones my house and lot, known as Number 638 Wabash 

 Ave., in the city of Chicago, 111., with the appurtenances and sole and unin- 

 terrupted use thereof, for one year, to commence on the first day of May next, 

 at the yearly rent of Six Hundred Dollars, payable in equal sums of Fifty Dol- 

 lars, on the first day of each and every month. 



R. DOE. 



An Assignment of a Copyright. 



To ALL WHOM IT MAY CONCERN: Whereas I, (name of assignor) of 



, in the County of , and State of , did obtain a 



copyright from the United States for a work entitled , and the certifi- 

 cate of said copyright bears date A.D. eighteen hundred and 



Now this deed witnesseth, That for a valuable consideration, viz 



to me in hand paid, the receipt of which is hereby acknowledged, I have 

 assigned, sold, and set over, and by these presents do assign, sell, and set 

 over unto the said (name of assignee) all the right, title, and interest I have 

 in the above book (or design, etc.) as secured to me by said copyright ; the 

 same to be held and enjoyed by the said (name of assignee) for his own use 

 and behoof, and for the use and behoof of his legal representatives, to the 

 full end of the term for which said copyright was issued, as fully and entirely 

 as the same would have been held and enjoyed by me, had this assignment 

 and sale not been made. 



In testimony whereof, I have hereunto set my hand and affixed my seal, 



this day of , in the year of our Lord one thousand eight 



hundred and 



(Signature.) [Seal.] 



Sealed and delivered in presence of 



Rule to Find the Horse Power of a Stationary Engine. Multiply the 

 area of the piston by the average pressure in pounds per square inch. Multi- 

 ply this product by the travel of the piston in feet per minute ; divide by 

 33,000. This will give the horse power. 



Example. Diameter of the cylinder, 12 inches; squared = 144 square 

 inches ; multiplied by 7854 = i, 130,976, as the area of the piston. The pressure 

 is 70; the average pressure is 50 pounds to the square inch. Multiply last 

 product by 50, gives 5,654,880 ; and that multiplied by the travel of the piston 

 per minute, which is 300 inches, gives 1,696,454 ; and that divided by 33,000, 

 gives 51 as the number of horse power. 



Power of Engines. Horse power in steam engines is calculated as the 

 power which would raise 33,000 pounds a foot high in a minute, or 90 pounds 



