Unlike a reserve, a sinking fund has no effect on the apparent profits of the period in which it is created. It does, however, tie up or render unavailable for dividends a certain part of those profits. Whether or not it is carried on the books in a separate account, a sinking fund is a part of the surplus of a business. =47. Computing Sinking Funds.= The amount necessary to set aside at the end of the year to provide a given sum in a stipulated number of years at a stated rate of interest, compounded annually, may be found as follows: Divide the interest for one year upon the sum to be accumulated by the compound interest upon $1.00 for the stipulated time. The result will be the amount necessary to invest at the end of each year. If the amount is to be invested at the beginning of the year, divide the result obtained as above by the amount of $1.00 for one year. _Example._ To provide for payment of $50,000.00 at the end of 15 years, what amount must be put into a sinking fund at the end of each year, if the fund is invested to earn 3% compound interest? Interest on $50,000.00 for 1 year at 3% is $1,500.00. Compound interest on $1.00 for 15 years at 3% is .55797. Dividing $1,500.00 by .55797 gives $2,688.32, the amount necessary to put into the fund annually. If this amount is to be invested at the beginning of each year, divide the above result ($2,688.32) by $1.03 (the amount of $1.00 for one year at 3%) and we obtain $2,610.02 the amount needed. BONDS =48.= In the sense here used a _bond_ is the written obligation of a corporation to pay a certain amount at a specified future date. Bonds are usually secured by a mortgage on all or a part of the property of the corporation. A bond issue is a favorite method of borrowing money with corporations. Bonds can be issued in any denomination, and by reason of this a loan can be distributed among a large number of investors. Being secured by mortgage on the company's property the bonds of a corporation are very frequently more desirable investments than its stocks. Interest on bonds must be paid before dividends can be declared. Bonds can only be issued with the consent of the holders of a certain per cent of the stock. =49.= _Classes of Bonds._ The bonds of corporations are of several classes, as follows: A first mortgage bond is one secured by first mortgage on the company's property. A second mortgage bond is one secured by second mortgage. Interest cannot be paid on second mortgage bonds until it has been paid on the first mortgage bonds. General mortgage bonds are those secured by a general mortgage on all of the company's property. Collateral bonds are secured by the deposit of collateral security. A debenture is a bond with no other security than the good name of the company. Refunding bonds are those issued in place of maturing bonds which the company does not wish to pay in cash.