It is an old proverb that " God helps those who help themselves." It might be said also that even at this late day the administration of justice remains so imperfect that the law helps only those who help themselves, so far as the protection of property is concerned. Even in countries where police duty is confessedly performed in the most efficient manner, and where a thief caught, is as a rule a thief condemned and punished, citizens feel it necessary to supplement the arm of the law by all the means in the ir powr. No departments of mechanical art have given birth to more numerous devices, or combined in a greater degree ingenuity and constructive skill than those whose products are designed for the protection of property against thieves and fire, these being the principal enemies which are to be combated on land. In the invention of locks there has been displayed a vast amount of study, thought,and ingenuity. All departmentsof science have been drawn upon to prevent thieves from withdrawing bolts that have been shot ; and one of the latest and most ingenious of these applications is that of magnetism, the subtile influence of which has enabled the combination lock, hitherto not inaccessible, to defy the most expert picklocks. The i ngenuity of honest men has been taxed to the utmost to circumvent the opposing ingenuity of rogues ; for it is nearly always the case that when some improvement stops these gentry for a time, they learn to surmount it, and the minds of inventors are again taxed to create new obstacles. A great deal of skill and talent has also been expended in the attempt to render walls as well as locks burglar proof; and as it was found practically impossible to do this on a large scale at a price within the means of ordinary persons, the practice of building burglar-proof boxes or safes, was introduced at a very early period ID the history of the world. Constant improvement has been requisite in the construction of these safes, as the re .purees of burglars have nearly kept pace with those of the safe builders. They have, however, at least, been partially brought to bay before chrome iron, chilled iron, and steel ; how long they will remain so remains to be demonstrated. In fire proof safes the problem is how to combat a fierce, but blind, unreasoning force, limited in its operation, and the effects of which are well known and understood. Much success has been reached in the construction of safes which will resist the action of fire for a long time. Of these .the most successful have been those which do not depend merely upon the non-conductivity of some substance to protect the contents from the action of external heat, but upon the power of steam to absorb and rapidly convey away heat. The water is generally inclosed between the external and internal walls of safes in the form of " water of crystallization" in some salt, alum being by far the best for this purpose, as it contains a very large percentage ot water. When the crystals of this salt become-heated they give off the " water of crystallization" gradually, and it is convertednto steam at 212. So long as this steam is generated the contents of the safe cannot be injured as the temperature therein can not rise higher than 212, no matter how great the external heat may be. Water has also been inclosed in tubes with plugs fusible at a low temperature, which, melting as the heat rises, allow steam to fill the safe. A vast number of inventions based on the above principle or upon others less reliable, have been made and patented, many of which have had their day, but some of which remain deservedly popular. How immense the distance also from the old fire syringes and buckets of medieval times to the superb and powerful steam fire engines of the present. How the "devouring element" must have laughed at those insignificant squirt-guns, in their impotent efforts to subdue it. The last ten years have given birth to two important additional means of security, namely, the Burglar Alarm Telegraph, and Safe Deposit Companies. Our readers are well informed in regard to the ingenious application of electro-magnetism, to the giving warning against the entrance of burglars through doors and windows. The principle is capable of extension, so that if, through neglect in setting the instrument, or by the superior art of the burglar, entrance should be effected, he could not pass about a building without giving notice of his presence. The Safe Deposit Companies afford facilities to people about to absent themselves from their residences, for the security of valuables while they are absent, and also for the safe keeping of valuables at any time. They were called into existence by a necessity, which ,as it must in the nature of things be permanent, will afford them a permanent support. The time is probably far distant when any or all the means employed for the protection of property from robbers will avail to give perfect - immunity from their encroachments ; still, with those now employed their profession would be rendered a most hazardous one, were the administration of justice as perfect as the mechanical devices intended to protect property from such marauders.