The present number closes the twentieth volumenew seriesof the Scientific American. In it we have striven to fulfill the promises made at the close of the last volume, and assurances have reached us from all parts of the country that our labors have been appreciated by onr numerous readers. In this effort we have adhered as much as possible to our former policy of popularizing science, and making it available to the masses. The great developments which are now making in all departments have each received their due share of attention, and progress in the mechanic arts has found a careful and impartial record in our columns. We are glad to learn that the valuable series of articles on the manufacture of beet root sugar which have found a prominent place in this volume, have largely attracted the attention of capitalists and agriculturists, and that there is a strong probability that this industry will soon be attempted on a larger scale than ever before in this country. Our subscription list has steadily increased, and the value of the Scientific Amebican as a medium for advertising has been recognized by appreciative patrons of that department. We are glad to learn also that many employers have acted on the hint we gave them at the close of our last volume, and are furnishing our paper to their employes, and, in other cases, inducing them to subscribe for it. Surely the information to be gathered from our pages is of the highest value to any young man who has any ambition to be other than a mere hewer of wood and drawer of water in this busy world. Our correspondents ask us many questions which are patiently answered. The information thus given forms a valuable department in our paper. We also receive much information of general value from esteemed correspondents. We trust that any reader who has practical information which he deems of value will not be deterred by modesty or fancied lack of acquirements, from communicating with us. Valuable facts, though clothed in ungrammatical language, are always acceptable to us. Give us the facts and we will attend to the grammar and orthography. It is encouraging to feel that we have the hearty co-operation of all our readers in making the Scientific Amebioan, par excellence, the mechanics' paper of the United States, but while we constantly bear in mind the requirements of this large and useful class of our population, we shall also endeavor to make our paper one which no intelligent reader, be he mechanic or farmer, or a professional, can afford to do without. Heartily thanking our subscribers for their liberal support which alone enables us to make and sustain as good a paper as we give them, we assure them that we shall not remit our efforts to furnish them weekly an intellectual repast which, we are confident, cannot be obtained for the same money anywhere else in the world.