EECREATIVE SCIENCE. 



103 



were, perhaps, more spiritual ; for, as Chris- 

 tianity spread, even Pagan rites gradually 

 assumed a less materialistic aspect, which is 

 shown in the devices, however poor in exe- 

 cution, which are found on the " consecratio" 

 coins of the last emperors. On a coin struck 

 by Maxentius to commemorate the con- 

 secration of his son E-omxdus, the kind of 

 type alluded to occurs. On the reverse of 

 this coin (engraved below) is represented a 

 tomb with the doors partially open, as for 

 the escape of the departing spirit, which is 

 symbolized by an eagle on the top of the 

 structure in the act of taking flight. No 

 human form is carried by the eagle, as in the 

 earher types of the consecrative coins, but 

 the spirit is deemed invisible, while borne 

 aloft to the region of the gods by the bird of 

 Jove. The inscription is aeteenae me- 

 MOEiiE (in eternal memory), and below, 

 M. OST. s., which, at length, would read 

 MONETA OSTIA SECTJNDA (denoting the 

 place where the coins were 

 struck) ; for the national 

 coinage was no longer 

 confined exclusively to 

 E-ome, as in the more 

 palmy days of the impe- 

 rial rule, but provincial 

 mints had been established in various districts 

 of the empire. 



A great variety of types of this last class 

 might be described, but they are so similar 

 in their leading characters, that little would 

 be gained of sufiicient interest to the general 

 reader, seeking rather the recreations than 

 technicalities of science. There are, how- 

 ever, certain ujiexplained types of similar 

 character in our early Saxon coinage, which 

 it might prove very interesting to inves- 

 tigate more fully, as they might turn out 

 to be consecrative types imitated from 

 those of the late E-oman coinage, instead 

 of mere "houses" or fortresses, as they 

 have been previously described to be. A 

 more careful examination may prove them 

 to be representations of tombs copied 

 from those of the late E,oman coins of the 

 " consecratio" types, and used on similar 

 occasions ; this, however, is at present mere 

 conjecture. In conclusion, I may add that 

 I he whole series of consecrative coins of the 

 Eoman empire, from those relating to the 

 death of the first Cajsar to those of the 

 latest of the degenerate emperors, forms a 

 most interesting field of examination and 

 study, which will yield an abundant har- 

 vest of recreation as weU as instruction. 

 The numerous varieties of type issued at 

 the consecration of Faustina the younger 

 might alone form the subject of a very inte- 

 resting essay. H. Noel Humpheeys. 



THE EXPANSION OF METAL, 



ILLUSTEATED BY EXPEEIMENT. 



It is well known that heat afiects the size of 

 bodies — an increase of temperature expand- 

 ing, and a decrease contracting them — and 

 although very little is known of the nature 

 of heat itself, some of its effects on bodies 

 which come within its influence may be even 

 rendered visible, when the amount of heat 

 applied is far below that of what we call fire. 



Every one is familiar with the efiect of heat 

 in expanding a column of mercury or spirit, 

 as in a common thermometer ; but probably 

 comparatively few have seen its effects on a 

 bar of metal — say of copper, for instance. 



The writer has for many years been in 

 the habit of illustrating the subject by 

 means of an original contrivance, which may 



